The HTC One M9 is a phone built on precision. It's a brand realising it made a pretty much perfect phone with the One M8 and doubling down on its greatest strength to try and win over more customers.
It's dropped the maligned 4MP Ultrapixel sensor of its predecessor, bumping it up to a huge 20.7MP option in a bid to attract those that feel safer buying a phone with higher numbers on the spec sheet.
And it's tied off the experience with a huge boost in the engine room and teamed up with Dolby to refine its already powerful BoomSound experience.
Even the battery capacity is improved, something HTC has struggled with in the past. It even beats the biggest rival of its time, the Samsung Galaxy S6, on that particular front. So has the Taiwanese brand managed to do the almost impossible and create yet another perfect device?
It certainly charged for it at launch: In the UK the HTC One M9 came with an initial RRP of £580 SIM free for the handset, with a good £10 per month extra on contract. US pricing had it for $649 without subsidy. These days, of course, you can pick up the HTC One M9 for a lot less.
With its successor the HTC 10 now on the market, you can grab last year's model for around £360/US$400. That's still far from cheap, of course, but then the HTC One M9 is built from premium materials, and contains pricey components like a full 32GB of internal storage.
The internals remain potent: an octa-core Qualcomm 810 chipset, 3GB of RAM, 2840 mAh battery on top of a Super LCD3 screen. The latter component hasn't got the cachet of Samsung's Super AMOLED display, but it's still color rich and seems close to the glass, which is important for image quality.
There are some things that haven't been improved over 2014's HTC One M8 though: the screen is still "only" 5 inches, which could be too big or too small depending on your opinion on the subject. The resolution is "only" 1080p, but again, some still question whether the pin-sharp QHD resolution is needed unless you're intent on using your phone in a VR headset, especially as it's harder on battery life.
The metallic chassis is back and is bolder than ever. It's a two tone design (well, the Silver/Gold and Gold/Pink versions have a contrasting band around the side, whereas the Gunmetal Grey and Gold on Gold versions don't) that uses a single piece of metal for the entire phone – it really feels better packaged than previous HTC phones.
However, the key question remains: is this package still good enough to warrant the extra cash when you can get the likes of the OnePlus 3 for a similar price? Have the improvements added more to the mix or is the HTC One M9 a sign of the company treading water, adding nuance rather than innovation?
Let's get this out the way at the start – the design is, by far, the most amazing part of the HTC One M9. HTC is calling it "jewellery-grade," with each one hand-finished by craftsmen, and it certainly shows.
The one-piece fascia is complemented beautifully by the two tone metallic rim (on my review unit, the silver and gold variant). The grey and gold versions will look less impressive, given they've lost the two-tone appeal, but that doesn't mean they won't be as nice to hold.
Actually, I'm pretty sure they'll be nicer than this model. There's something about the design right now that I really don't like, the rear edge proving to be quite sharp in the hand. It's not going to draw blood, but when I used the gunmetal grey preview device in Barcelona back in early 2015 it definitely felt closer to the One M8 in style, with more of a comfortable curve.
The reason for this hasn't been confirmed by HTC, but I get the feeling it's something to do with the coloring process.
Whatever the case, it's perhaps telling that HTC ditched this two-tone effect and the associated stepped-edge design for the HTC 10.
The other thing that's changed here since the HTC One M8 – and not for the better – is the power button transferring to the right-hand side of the phone.
This is a more natural place for it to live, making it easier to turn the screen on and off. However, HTC has inexplicably made it the same size and shape as the volume buttons above, so feeling for it without explicitly looking means I often hit the volume key instead.
Again, HTC altered this button balance in the HTC 10, which could be seen as another admission that the M9's design isn't quite optimal.
The microSD slot is right above the trio of buttons too, and as it's slightly indented can cause confusion when trying to change volume in the pocket. It's hard to tell which is which, even with the phone in your hand – the extra ridges on the power button don't help enough.
While the decisions HTC has made to improve the One M9's design don't seem to have hit the mark, there's no doubt this is a finely crafted phone, and was probably the best on the market at launch in that respect.
The two-tone finish is superb and still quite distinctive more than a year on, the weight and balance is even better than before, and the precision I spoke of earlier is the overriding feeling.
The sharp edges of the BoomSound speakers are well-defined, and while it's heavy at 157g, especially compared to contemporaries like the iPhone 6 or Galaxy S6, Apple's is the only device that can come close to beating the attractive packaging here – and I prefer the weight and balance HTC has created.
I'd definitely chuck it in a case though. After two days I'd already dented the bottom through it falling a foot onto the floor, and those nicks are really noticeable on the premium casing.
I also checked out an M9 handset more than a year on from launch and, while generally in decent condition, there were tiny stress cracks in three of the four corners where the display glass meets the metal.
Yet another M9 handset I tried recently didn't have this latter problem, but there were visible scratches around the microUSB port where the metal edges of the charger connector had made their mark. It seems you pay a price for such a fine metal finish, then - though that's hardly a unique criticism for a modern smartphone.
One thing HTC gets lambasted for is the extra space around the screen, with people saying the HTC logo doesn't need to be on there, surrounded by a black bar that many think is there for show.
It isn't. It's packing screen components that have to go somewhere as HTC has extended the length of the One M9 through the need for decent audio chambers to pump out BoomSound – and I'd rather have the powerful speakers than an identikit smartphone.
The M9 is actually a little smaller than before, despite having the same 5-inch screen as the previous year. In fact, it's an identical screen to the HTC One M8's, with a 1080p Super LCD display covered in Gorilla Glass.
There are undoubtedly performance improvements, but like the older model, HTC is being cagey about them. What is apparent is the screen's colors are rich enough, the gap between glass and display is low and the response under the finger is noticeably sharper.
That said, in our testing the screen is too dark under auto conditions, the colors often appear washed out compared to the rest of the flagship phones of 2015, and it doesn't pack the same 'wallop' as the iPhone 6 or LG G4, for instance. It's not terrible at all, but it begs the question why HTC didn't update this key component.
I don't want to harp on about the HTC One M9's successor too much here, but it's difficult to argue that the HTC 10's QHD Super LCD 5 display didn't arrive a year too late.
Still, the M9 screen's 441PPI is perfectly sharp and doesn't really offer a lot less than the QHD screens that are starting to flood the market.
The only functional reason I can see to stick a super-sharp display into a screen below six inches in size is to allow for virtual reality headsets, which magnify the screen and can cause pixelation. However, HTC isn't using the phone as the base of its VR Vive headset, so there's not really any need here.
Google is set to launch an ambitious new universal VR headset in Daydream later in 2016, of course, but even that will require brand new smartphone hardware that isn't on the market yet.
The HTC One M9's 5-inch screen is a fraction smaller than the competition on the market right now, with many other brands choosing to go 5.1-inch and above – but again, 5 inches seems like a fine choice here.
There's a fair amount of bezel on the One M9 compared to other 2015 flagship phones like the LG G4 and the Galaxy S6, and that's more pronounced due to the extra metallic lip that's running around the edge of the phone.
But we don't need edge to edge displays unless that's what the phone is about – and HTC's model is geared towards feeling more ergonomic in the hand, so it seems to suit the device.
Thinking about what's changed with the One M9 is where you'll realize that HTC really did hit a roadblock when it comes to innovation.
For a brand that's been so heavily into bringing something extra to the smartphone table – think BoomSound speakers, the duo camera, finding a way to get phone signal through an all-metal body – there's very little to shout about here.
It's disappointing, given I've become used to HTC being the go-to brand for cool new ideas – making the same phone as the previous year with a little more polish leaves me a little deflated.
And yet the phone costed so much more than in previous years – it's even more than an iPhone 6, initially. Of course, the market eventually corrected itself, but it's left a nasty taste in the mouth that the brand was asking for more just to get a slightly more refined design.
What's better than hearing things? Hearing them in three dimensions of course! And that's just what HTC says it's done here, adding Dolby support to its BoomSound speakers (both with and without headphones connected) to create a virtual surround sound.
What this seems to mean in the real world is that the phone can now pump out sound for "theater" or "music" mode, and further improve the sound quality when you're listening to tunes over headphones.
HTC has also created its own range of earbuds to allow you to get the best out of this optimized sound too, taking advantage of the extra power for your ears. It even offers different sound profiles for each of these sets.
HTC has gone bold and ditched the Ultrapixel camera for the new One M9 - well, ditched it from the rear anyway. Last year's sensor is now used on the front of the phone; with the low light ability making selfies look much better.
The rear camera is now a 20.7MP affair, a very similar sensor to the one found in the Sony Xperia Z3 (although made by Toshiba).
It's been heavily revised, and now offers a much sharper image for those that like to zoom into photos. It's lost a little of the low light ability, and colors are more muted, but overall is a much sharper and more competent sensor.
Four more cores
The HTC One M9 is powered by Qualcomm's Snapdragon 810 chipset, which was its top processor of 2015. This offers two sets of four cores (with only one set ever working at any one time), clocked at 1.5GHz and 2GHz.
That's backed up by 3GB of RAM, and this combination results in a very fast experience under the finger. It's not perfect still, as Android Marshmallow still seems to get in the way when doing things like pressing the multitasking button and letting the phone lag.
Like a lot of things on this phone it seems that it's fine when 'warmed up' - pressing the multitasking button will lead to a pause the first time, but press again and it's instant - but the first load is slow.
And there's the issue of heat. HTC and Qualcomm were subjected to some bad press in 2015, with the insane power of the 810 chipset meaning you can really run this phone hot through benchmarks and gaming, although not to the levels being described thanks to recent software updates.
In reality, the phone does get rather warm at times thanks to the metal body dispersing heat more evenly, and while it's clear the Qualcomm chip is running to a higher temperature it's nothing massive.
Go and go and go
The battery life on the HTC range has always been something to keep an eye on, as I've always found it rather 'slippy'. That means that even doing general tasks like browsing the web or checking football scores will munch down battery life a little fast.
The One M9 has tried to eradicate that problem by using the Snapdragon 810 chip (which can use a lower power set of cores to get you through the less taxing tasks) as well as whacking in a relatively meaty 2840mAh battery, which is only fractionally smaller than the one used in the iPhone 6 Plus.
It's even bigger than the one used in the Samsung Galaxy S6, and combined with the lower pixel count should enable HTC to get a better battery life out of its flagship range.
Except, well, it doesn't. You can read more about this in the Battery section of the review, but HTC still seems unable to build a light interface that doesn't eat power when you don't want it to.
Looking at the statistics it seems that Android updating certain Google services is the main culprit, which is something usually associated with early software, so future updates might solve this. It took a while, but Android Marshmallow has finally started rolling out in 2016. However, we're only really noticing an improvement to the battery when not using the phone, and that's thanks to Google's new Doze feature.
So it's an OK battery life for HTC, and one that might get you through the day - especially if you're not a heavy user. But it will be close - and it's worse than the battery life on the One M8.
Here's a big win for HTC: the base (and only) level of storage on the phone is 32GB, which means any apps that need to be kept on the phone's internal memory can do so happily without leading to the dreaded 'delete apps to free up space' message when you need to take a picture or download new software.
There's also a microSD slot on board to allow you to get more storage in there as well, with the upper limit of 128GB bringing the total available to 160GB for your One M9.
It's worth remembering that putting loads of extra info into the phone via memory card can have an impact on performance, so don't chuck too much on there that you'll need to use regularly as it will slow the phone down somewhat.
HTC's Sense UI was overhauled again for the HTC One M9. Sense 7.0 comes with a few little tweaks - although it really looks very similar to the one we got before.
The big changes are through themes and the gallery, with both having a marked effect on the way you personalize your phone. The theme generator is actually pretty cool: take a snap of anything, the phone will analyze the image and create a full palette of colors to use with icons and app headers - plus the font and icon shapes will be altered to match the overall 'ethos' too.
You can choose different styles if you're not completely happy with the way the phone's suggestions work - but it's a very holistic way of making a picture work throughout the phone.
In keeping with HTC's more recent policy of updating such components separately from the core Sense UI, you can also apply the freestyle layout themes introduced with the HTC 10. These let you use and freely position stickers in place of app icons, giving your home screens a more organic and artistic look.
Practically speaking, I found this option a little awkward - I just wanted to be able to put my finger on the app icon I wanted at a glance - but I suspect that plenty of people will love the customization potential it offers.
Indeed, using the HTC One M9 at various points throughout 2015 and 2016 has shown that HTC is shaping and remoulding its Sense software experience on the fly, which can lead to some friction.
For example, the Cloudex service we mentioned in our original M9 review subsequently changed its name to the One Gallery app, before support was withdrawn altogether at the end of April.
This then left a useless shell of an app icon in the app tray where once there was an interesting new way to collate images from multiple sources. Now, after the Android 6.0 Marshmallow update, there's no sign of the service at all
One of the interesting things about phones from the last few years was their ability to track fitness, the idea being that they'll always be in your pocket and therefore will give the best amount of info.
Despite partnering with Fitbit in 2014, HTC decided it needed its own version of a health tracker: HTC Fun Fit. You'll need to download this though, which is a shame – especially when you see some of the pre-loaded apps on the One M9 that I could live without happily.
Then again, Fun Fit doesn't seem like there's a lot of point to it for a number of reasons. Firstly, the rise of the fitness tracker has shown us that the phone is only so good for tracking steps, as it's not always in the pocket and therefore might not get all the data.
Secondly Fun Fit seems very limited beyond giving you information on what you've done in terms of steps taken or time spent running / walking. It's also a little useless, giving wildly incorrect results when working out how long you've been running for.
As part of a larger app, this stuff is great – and I love the cartoonish avatars, the ability to instantly sync up with friends using the app on Facebook and the different levels of activity on offer as you trot around through the day.
However, there's no end game here with HTC's option. No training plans or motivation to do more – so who's this for? The average non-exerciser will idly look at it, intrigued by their stats at the start, but with no motivation to go further.
It's a good app in that it's well-designed, but that's about it. If you're after a fun, polished casual fitness app, you're better off with Google Fit.
Interface and performance
The Sense interface on the HTC One M9 is still one of the most cultured and sophisticated around – far better than Samsung's TouchWiz and far more powerful than iOS - and with either Android Lollipop or Marshmallow (most in the UK seem to have updated) currently powering things, it's been given another boost forward in terms of functionality.
This includes the availability of Google Now on Tap. Press and hold the virtual home button, and Google's assistant will scan all of the text on screen - whatever you're doing - and provide contextual information.
For example, while reading a techradar article about the Samsung Galaxy Note 7 and Gear VR, Google Now on Tap provided links to Google searches on both devices, as well as on the security camera that was being advertised. Now on Tap still isn't quite where it needs to be in terms of surfacing consistently useful information, but it has promise.
Still, most of the tweaks here take place as part of Sense and, increasingly, HTC Service Pack, so the actual Android version isn't as important a consideration as it used to be.
In general, it's Sense as usual. There are still a lot of swipes needed to get around, which may put some people off, but it's simple to pick up and rewards you for playing with lots of subtle tricks.
The interface hasn't really been overhauled that much in the last few years, and given most of the updates below will be coming to the HTC One M8 it seems like the reason to get them on the current model is slightly limited.
That said, they're still great ways to drive through the phone, and the nimbleness of the Snapdragon 810 chip means most of the touches are buttery smooth and quick. There are still pauses, judders and stumbles though, which I don't expect in a phone of this level.
In our testing, it's not got the same speed at all when compared with the iPhone 6, LG G4, Samsung Galaxy S6 and Sony Xperia Z3. It's very slow compared to the first three, taking an age to boot, to load apps and to generally keep things in the cache.
In a vacuum you probably won't notice it too much, but in comparison it's lagging.
That point I just made about HTC Service Pack making the question of which Android version the HTC One M9 is running less of an issue is perfectly illustrated with BlinkFeed. We've had two fresh test units in since our initial review - one still running on Android Lollipop and Sense 7.0, and the other running Android Marshmallow and Sense 7.0. In both cases, BlinkFeed has changed since our initial review.
HTC's custom news feed is still located to the left of the main home screen, but now it's a little different. I've noted before that there was something about BlinkFeed that hadn't evolved in the way I wanted it to, even though I was promised three years ago it would become really intuitive. It seems HTC agreed, but it still hasn't gone far enough.
Towards the end of 2015, BlinkFeed changed into a service platform for aggregating content from partners. Right now, that mainly means News Republic.
Scroll left now and you'll find the Highlights screen, providing a random selection of news stories from around the web, alongside any appointments for the day from the Calendar app. Once you've tapped to download the News Republic app, you'll have more control over which of these stories are surfaced.
You also get Yelp recommendations for local lunch spots, which will occasionally show up on your lock screen. Ideally, this service should know the EXACT moments that I'll be looking for a new place to eat (when calendar invites show lunch, for instance) rather than just generically. But at least it's working in the UK now, which it wasn't at the time of launch.
Is any of this an evolution of the original BlinkFeed concept? Not really, no. In fact, it's pretty clunky that you have to download a whole third party app just to get the news portion to work properly now.
This isn't something that's particularly new, but for those of you thinking about upgrading from the HTC One M7 or another phone from 2013, the improvements on Sense are really cool.
The lockscreen now shows information in strips which can be flipped away when not wanted, or double tapped to open in the relevant app. It's a neat system, and shows Google and HTC have worked well together to integrate the option with Sense.
In the pull down bar, there's often a lot going on though. With Google Now just chucking information at you (you'll get the option if you search for anything in the dedicated bar on the home screen) as well as apps telling you information, music widgets popping up and more, it's quite busy.
Another pull down will show the quick settings and the integration of all this together makes a lot of sense to me. It's one of those things to be experienced rather than read about, but with a few minutes of use it all makes sense.
Sense Home is one of the big things HTC is talking about with the One M9, a widget that lives on the home screen to show you the apps you use the most.
The clever trick is that the phone will work out where Home, Work and the more generic 'Out' zones are, and populate the apps accordingly - and you can set these locations yourself.
It generally works well too, although you can't tell it to NOT put certain apps there - Tinder fans probably won't want others to see that on the front screen.
By default HTC has also lobbed 'smart folders' into the mix, showing suggested apps and those you've downloaded.... but these are really poor and should be switched off. The suggestions are random and the titles truncated - not what you'd expect from a flagship phone.
I like the idea of having different apps for different times, and generally they were pretty good. However, I still found that after a week the eight slots weren't filled with my most-used apps, so I hope this gets more accurate over time.
Gestures are back from the HTC One M8, allowing you to wake the phone into certain modes when locked. The main gesture is double tapping the blank screen to unlock it, something Nokia invented and LG made popular. Given how hard it is to find the power button at times, this ability is useful - plus you can now double tap to turn the screen off too.
Flicking up from the bottom of the display bypasses the lock screen altogether if you've not got security on, and when I remembered to use it I found it quite a useful ability.
Plus you can drag down from the top or other side to open straight into voice dialing or Blinkfeed, although these are turned off by default.
The main thing that's annoyed me from before is still there though: if the phone is asleep on the desk, you can't wake it without picking it up or knocking the One M9 first. I'm sure the screen doesn't stay constantly waiting for a tap or swipe input when asleep to save battery, but the LG range seems to be able to do it with better power management.
But this gesture unlock is one of the bests thing HTC has added to its software in recent times, and it should be applauded for keeping it present.
While I don't want it to sound like I'm bashing the One M9 too much in the interface section, the keyboard is another place where HTC has let a lead go.
The brand used to be synonymous with an excellent and accurate keyboard, but it's so far behind the likes of SwiftKey that it's hard not to recommend you don't download a better option from the Play Store as soon as possible.
The accuracy is OK, but the word predictions aren't always correct. On top of that, the phone will only let you put in a word that's not in the dictionary if you explicitly tell it to do so - and it won't default to that the next time.
It's not terrible, but HTC used to be the best default keyboard on any phone, where now it's just OK.
Excellent contact integration
One thing HTC does do really well is make the phone section really easy to use, with the clever join between your contacts on handset and social networks almost seamless.
For instance the smart linking between your friends on the phone and the profiles on Facebook and Twitter is excellent. And on top of that, the One M9 can pull in HD pictures from Facebook profiles so when you get called it's not from a blurry, pixelated mess.
It can take a while for the app to overwrite the fuzzy pictures with the HD options, but it will shake itself out eventually. Given phones like the iPhone 6S still can't get close to this kind of happy integration (nor do they have smart dialing, where you can easily tap out numbers to get to friends' profiles) so HTC should be applauded for this effort.
The performance of the HTC One M9 is decent, as noted. There are still a few judders and delays around the Sense UI that I had hoped would have been ironed out by now, but when it's opening apps or searching the web everything is reasonably crisp.
I wish I could it say it would stay that way for the next two years that you'll own this phone, but when you start filling it with apps you'll get an inevitable slowdown as they start doing things in the background.
Always keep things clean and safe, kids. A factory reset once in a while doesn't hurt.
The Geekbench 3 results show a fairly impressive score, and remember this isn't really the full performance of the phone as HTC has throttled it slightly so it doesn't go burning hot.
That points out something huge about today's phones: they're pointlessly powerful. The octa-core processor can be pushed to insane speeds if you don't care too much about battery, but in day to day life it won't hit anywhere close to that limit, meaning HTC can dial back the power without a worry.
With that in mind, why does it matter how powerful the phone is? It's like buying a high performance sports car that will never see the track. It's good to know you've got that headroom to put your foot down when you want it, and the acceleration is great, but push it too hard and you'll be in trouble.
Even with the lower power, the HTC One M9 is perfectly capable - though it's right in the middle of the flagship pack for its generation. An average Geekbench 3 multi-core score of around 3700 puts it well behind the Samsung Galaxy S6 on 4900, only a little above the LG G4 (3500) with its supposedly inferior Snapdragon 808, and comfortably ahead of the iPhone 6 with 2905.
For gaming, flying through multiple apps and more it's got the power – but then when you're trying to browse high resolution pictures in the gallery and it takes a few noticeable fractions of a second to load the fully sharp image, that experience is tarnished somewhat.
Shout out for call quality though – the ability to grab signal is very good indeed, which is even more impressive when you think how much metal is in this phone.
Metal usually equals no phone signal at all, so it's good to see that HTC has somehow managed to improve this area. I was a really big fan of using the One M9 to make something as old-fashioned as a phone call.
Battery life on the HTC One M9 should be brilliant in comparison to what's been before. With the HTC One M8, the Snapdragon 801 chipset finally made an HTC phone decent at lasting throughout a day, and with a larger power pack and an improvement from Qualcomm things should have been awesome.
Sadly, they're not. I'm not saying that it's a problem and this phone won't last long enough to tap out a couple of tweets, but the performance hasn't been moved on much from previous efforts.
The issue is that the phone heats up really easily doing the most mundane of tasks. Anything that takes a little bit of wireless connection is a quick way to watch it drop, be it mobile data or listening to music over headphones.
Where most phones these days won't have much of an issue losing no more than 10% on my morning commute, even with a bit of video action, the One M9 has dropped as much as 17% through Bluetooth music streaming and emails, which is odd as this doesn't usually munch too much power.
The good news is Google's Android 6.0 gives you a good way of checking the problems, letting you shut down (or get rid of) the apps which are misbehaving.
However, in this case it's 'Google Services' which is one of the core power munchers. This incorporates elements fundamental to the running of the phone, which means there's not a lot to be done about it.
I usually see this in the first few days of reviewing, but the issue has pervaded. Hardcore testing - be it standby, heavy apps, web browsing and YouTube videos, for instance - has proven the HTC to be a poorer choice than the rest of the competition, with poorer background battery management.
This means you can't lean on the One M9 too heavily for playing games or watching videos, which is irritating if you want to have a little bit of battery left at the end of the day.
Gaming is really heavy on the battery, with a quick 15 minute game sometimes sucking 10% juice - although the issue is often that mobile games these days are constantly communicating with servers for online play or in app purchases, which hurts the battery.
Running TechRadar's standard battery test on the One M9, where we looped a 90 minute full HD video at maximum brightness showed that the M9 was one of the worst performers of recent times, with 24% of the battery disappearing - though I should note that this represents a 7% improvement on the same test we ran near the phone's launch. HTC and Google appear to have improved matters.
Still, if you consider that the LG G Flex 2, another big phone on the market with the Snapdragon 810 chipset, only lost 13% in the same test, then you'll see that there's something fundamentally inefficient going on with the software here.
That seems to be borne out by running the same test on Lollipop-equipped HTC One M8 and HTC One M7 handsets, which managed 24% and 30% respectively - and the phone from 2013 had barely enough battery to make it through the day too. This shows that HTC effectively stood still in battery life terms from 2013 to 2015, even with the larger capacity and theoretically more efficient processor of the M9.
As I said, the One M9's battery does appear to have improved since the early days, but that's only resulted in parity with the One M8, which can be had for significantly less than its successor these days, and that's just not good enough.
The Android 6.0 update appears to have brought some benefits, but only really in terms of idle time. Leaving the phone more or less untouched, with only extremely limited usage (as in, not using it as my main phone for a time), I found that the phone could last through a good three days.
That's doubtless thanks to Google's Doze feature, which was introduced with Marshmallow. Doze minimizes power usage when the phone is still and in sleep mode, and it really works. Of course, this benefit is largely nullified if you use your phone with any kind of regularity.
The other big thing here is QuickCharge 2.0 – although this offers a pretty amazing 60% charge in just 30 mins, the charger in the box isn't QuickCharge enabled to get the maximum speeds on offer.
This is just ludicrous – I thought by this point that they'd be standard as the tech began appearing in phones in 2014. It's really frustrating that you'll need to spend so much more given this is an already expensive phone relative to its specs.
HTC briefly gave up on the UltraPixel idea with the One M9, at least for its main camera. Instead it's gone for the same 20.7MP sensor found in the Sony Xperia Z3, aiming to wow with the higher number of megapixels stuffed in.
That temporary step away from UltraPixels (the HTC 10 brings the terminology back) is a big disappointment, as HTC was the one big Android brand striking out against the need for loads of pixels to take a good picture, instead going for the innovative combo of a 4MP sensor that could nab loads of light and a secondary sensor for clever effects.
HTC was evidently trying to stand shoulder to shoulder with similarly spec'd offerings from Samsung and Sony, but it's only been partially successful. A good camera today needs to have a fast start up and shutter speed, excellent detail, accurate color reproduction and good low light performance, and it's clear HTC has gone in hard for all of these.
The One M9 generally has a very good performance in most conditions, whether it's low light, bright scenes or changeable conditions. The sharpness of the pictures is clear and the color tone, although a little more muted, looks more mature than the over-coloration of the One M8.
What's clear is there's a lot of post-processing going on throughout the photography process, and it's very good for the most part. It's evident that HTC has tried to offset the loss of low-light performance by boosting the exposure after the shutter is pressed – but this results in a lot of noise.
The flash isn't brilliant either, with the high power light taking over night pictures. The amber LED in there is designed to help improve skin tone, and while it does do that, the entire snap is a little over exposed.
The big annoyances here, though, are the shutter speed (and, to an extent, the start up time, which is far behind the iPhone 6 and the Galaxy S6) and the time taken to autofocus as well.
The biggest culprit was HDR mode, which forced the One M9 to pause for a while before even beginning to start processing the shot in darker conditions. Again, this isn't the sort of thing I'd have expected from a recent flagship processor.
And the result, thanks to the lack of autofocus and the slow start to processing, is often muddy and lacks definition.
So while low light performance has dipped appreciably, the general performance has more than improved enough to take its place. In general daylight, I was really impressed with the performance of the One M9. OK, it's nothing different to the rest of the market, but it gives you quality and sharpness time and again.
The field of view is lowered though, thanks to the higher number of megapixels. This means you don't get as much info into the sensor, and where Apple is improving this year on year, HTC just took a step backwards to get more pixels into the mix.
The front facing camera, now using the UltraPixel sensor from the rear of the One M8, is miles better.
It captures a huge amount of detail and really removes the need for a flash – something a lot of people have been calling for on other handsets.
The beauty modes are still present, with the ability to smooth skin and increase the size of your eyes to a scary level. Face fusion, where you can work out what the demon spawn of you and your friend would look like, is also offered – and great fun down the bar.
The other area that HTC has traditionally been strong is the after effects party, with the Zoe ability to take short videos and mix them with pictures a really cool trick.
This year, Zoe has been moved to a separate app, been taken off as a camera option and been replaced in post processing with a lot of, well, useless effects.
I don't really get why HTC is making such a big deal about the ability to do things like double expose your photos – they just end up looking like you've messed up two snaps, unless they happen to perfectly complement one another.
Similarly the prism and stripe effects, allowing you to 'remix' your image – it just seems like a good way to create a Pink Floyd album cover. It doesn't make them look any better, and it's certainly not something I'd share on social media and be proud of.
One area that HTC has firmly wedged itself into is entertainment: whether that's using the phone for watching movies, listening to music, playing games or even letting it control your whole media system, the One M9 is really rather good for all of these things.
The BoomSound speakers should get the credit for a lot of things here, as they're the reason that HTC has managed to bag the tag of being so good at audio.
When I first heard what HTC was doing with these in 2013, I thought it was a stupid idea - making a phone better at playing sounds out loud was just going to appeal to the juvenile delinquents who play tinny music on a bus, right?
But then I found that I would put music on when working at home, show YouTube video to friends and even use the handset without headphones when using guided exercise apps - things I've never done before with a standard phone.
The sound is rich and loud, the extra space HTC allows meaning there's a lot of room for the audio to echo and gain in timbre. In short, it worked - and even the internal BoomSound optimizations were smart. Using the technology again makes sense - I'm still not convinced that the speakers couldn't have been made smaller in the same way as on other Desire devices in the HTC line.
It seems this is equal parts branding as it is technology holding back - HTC wants the speakers to be seen to give the impression of a flagship phone. I get that, but a slightly sleeker device would have felt like a step forward.
Still, in slimming down the HTC 10 for 2016, HTC has arguably made its BoomSound technology worse, meaning that the HTC One M9 remains the best-sounding smartphone around. They can't win, can they?
Enough of the look of the speakers though - how impressive is the audio capability of this phone? Very good, putting it simply.
The HTC BoomSound integration with Dolby technology really does improve the quality of the music, whether with or without headphones.
When listening to music through the speakers, the One M9 will automatically add a notification at the top of the screen to let you know which 'mode' the BoomSound speakers are pumping audio out in, either theater or music.
It's irritating that the phone doesn't switch this automatically, as it's clear that if you're using Netflix you'll need to be in theater mode, and if Spotify is up, then it's music.
Speaking of the streaming service, the music app on the One M9 is starting to feel a little redundant given the popularity of on-demand music, which explains why nothing has really changed of late with the app. At least Google has changed the Google Play icon, so now you won't confuse the two previously similar logos.
If you do have a full audio arsenal of MP3s to throw onto your One M9, then you'll be pleased with the experience, as it's got downloadable lyrics, clever visualizations and a bright and clear interface.
There's no hi-res audio on offer though, and this is starting to trickle through as something people are looking for in a phone. HTC finally jumped aboard with the HTC 10, but both LG and Sony were making a big deal of it around the time of the HTC One M9's launch, so its lack of support is a shame.
I don't think HTC has missed out too much by not including it here, as hi-res audio remains somewhat niche, but it would have been a nice improvement.
Watching video on the HTC One M9 is fine, although the automatic brightness settings are a little on the dim side. Even watching stuff in bed, where a low brightness is OK, I found that I wanted to keep pushing the clarity of the display up, which obviously affects battery life.
HTC still hasn't got a dedicated video app, but tapping on a downloaded or sideloaded video will bring up a 'View video' option alongside Google Photos in the 'Open with' menu. You can also access your video content through the Gallery app.
Whichever method you choose, the sharpness and contrast ratios are impressive, and if you've got the phone propped up somewhere then the BoomSound speakers make a nice addition.
I've yet to notice anything coming close to Dolby virtual surround sound coming out of them when it comes to watching video though. To me, surround sound is when you have moments where you're not sure if there's someone approaching to the side - all I felt here was that the dialogue was clearer.
That's not a bad thing, but don't get excited and think that buying this phone will replace a home cinema system. Then again if you did, I'd worry for your sanity.
Peel Smart Remote
HTC's SenseTV app has disappeared, to be replaced by the Peel Smart Remote option. Given this was the power behind the app originally, it makes sense that HTC should cease bothering putting its own skin on and let the current app do the talking.
It's an odd app in terms of quality, ranging from the sublime to the ridiculous. When displaying what shows are on, or those you might like, the pictures look low res and stretched as it pulls them from the local channel servers.
Given this is one of the first things you'll see when turning on the app it won't fill you with glee.
But go a little further and you'll see that this is a very powerful app indeed. The set up for the main TVs couldn't be easier, and by simply entering your post code the channels are almost always spot on.
In less than 30 seconds of powering up the app you can be browsing channels and watching a TV that you've not been able to use remotely for years (we've all got one where the remote has been missing for a while, right?) and setting up a TV from a big brand is speed personified.
The interface is slick and easy to use, and the ability to call up the EPG on the remote screen is really cool. Plus I can never tire of pressing a button for a channel and watching the phone press all the buttons in the right order to make sure that the right pictures pop up.
Who doesn't like automation like that?
One annoying thing that kept happening was the fact programs I'd just watched and decided not to continue with remained in the notification bar, even if the app was closed down.
I'd wager that HTC's biggest problem here is letting people know that their phone is such a powerful remote. Given so many people asked me what the top section of dark plastic was for on the phone, it's clear not many know that this is a device with an infrared blaster packed in.
But if that's HTC's hardest problem to solve then it's not a bad thing at all.
The Adreno 430 GPU in the HTC One M9 is definitely strong enough to be one of the better options on the market for general gaming - in fact, there's very little that can be thrown at it that will cause the phone to crash or stutter.
That means you can play something like Vainglory or Dead Trigger 2 and combine it with the rich sound from the BoomSound speakers to get a really decent experience, and the sensitivity of the touchscreen is something that makes it a real joy to use.
Sadly I'm still yet to find a phone that really does let me use it as a console, with an easy connection to the TV with a Bluetooth controller attached.
What fails to work here is the latency: connecting the phone wirelessly or through a MHL lead (which is supported) still results a slightly laggy experience if you've got a controller attached through Bluetooth on the phone, so all that raw power can't be exploited.
As a mobile gaming unit it's pretty good - as long as you can handle the dramatic loss in battery power - and I've not found much incompatibility for titles on the One M9.
The HTC One M9 is a very good phone, mostly let down by the fact the one from last year was brilliant. The only reason it's judged so harshly is the fact that it's got so many other brilliant phones to steal its thunder - so if you're looking for an alternative, these are the ones to look at.
Samsung Galaxy S6
The Galaxy S6 is definitely the phone of this era that most HTC users will be thinking about instead, especially if they're into the Android ecosystem.
While HTC managed to reboot its ailing flagship franchise three years ago, it took Samsung until 2015 to manage the same thing - and boy, has it done it. The Samsung Galaxy S7 represents a further refinement, but the Galaxy S6 can be picked up for around the same price as the HTC One M9, and it's still a strong performer.
There's nothing particularly outstanding about the S6, but it manages to do everything very well. The camera is feature-packed and offers up brilliant snaps, with a more-than-decent 16MP low-light sensor. The processor is an Exynos 7420, built in-house and hyper-powerful, and the QHD screen really adds clarity to the mix.
However, that's likely more to do with the Super AMOLED technology underpinning than the crystal clear resolution on offer - after all, there's only so much sharpness the human eye can discern. It doesn't stop images looking amazing on it though.
The main issues you'll have to deal with are poor battery life - with a smaller battery pack and higher res screen, it's understandable that this would be slightly shorter in the power department.
All of the other alternative picks we discuss here are of a similar age or even older than the HTC One M9. The OnePlus 3 is a good year fresher, with a larger and more vibrant 5.5-inch AMOLED display and a significantly faster Snapdragon 820 CPU with an unusually high 6GB of RAM.
It also has a similarly accomplished - if not quite as flashy or refined - all-metal design, and the OnePlus 3 also has the advantage of a fingerprint sensor for speedy and secure access. Its camera is similarly competitive, too, whilst hardly being outstanding.
Despite all this, the OnePlus 3 costs £329/US$399 (around AU$450) brand new. It's difficult to justify the purchase of a less current and generally inferior phone for similar money.
And we come to my biggest issue, that the predecessor to the One M9 is actually a little bit better.
While it does lack in terms of spec, it manages to more than make up for it in cost, coming in between half and two thirds the price of the One M9.
And I can't really say what's that much worse with it. The battery life is actually a touch better, the build quality not miles away and the camera not terrible in comparison. OK, the new 20.7MP camera on the One M9 is stronger, but it doesn't have the innovative Duo Camera sensor for really cool effects.
The Sense experience from the One M9 has made its way to this device with Android 6.0 too - so really, with the same screen, a more palatable price and a little longer in the battery, is this actually the better phone?
HTC released another interesting phone in between the One M9 and the HTC 10, and it's called the One A9. Many have criticized HTC for mimicking Apple on the design of this phone, but we still think it's a great looking handset that stops people in their tracks.
It comes with Android 6.0 Marshmallow on it, which the HTC One M9 has only belatedly caught up with. But the battery isn't all that powerful on the HTC One A9 so it may be worth going for the One M9 if you're a heavy user.
There's also a great 13MP camera on the back of the HTC One A9 that takes just as good images as the HTC One M9, if not better. If you're looking for something from HTC, it's certainly worth checking out the One A9 before you just decide on the One M9 - though you may need to shop around online to find one.
The LG range is always going to be a thorn in HTC's side, as it can offer a premium smartphone experience for a lower price, as it channels its marketing budget back into the phone's cost.
The QHD screen is the real talking point here, but it doesn't really offer that much more than HTC does, and the build quality of the M9 far outstrips the weird leather the G4 is packing.
For the price - you can grab the LG G4 for less than £300/US$300/AU$450 now - it's a tough call. If you're not fussed about design, the G4 is cheaper and faster with a better screen and camera (although not as much power) - but it does have a leather back, for some reason.
Sony's Xperia Z5 is a big improvement upon the phones that have gone before. This time there's a new luxurious design with frosted glass on the back and then there are metal edges for the first time.
There's a new fingerprint sensor on the side and considering this is the first time Sony has managed to integrate one into the phone, it works surprisingly well.
There's no wireless charging here, but the Xperia Z5 has some of the best battery life we've seen on an Android flagship phone for quite some time.
And then there's the camera. It includes a 23MP sensor with a new autofocus mode that means you're able to take snaps of fast moving objects and catch the action. It's a big upgrade from Sony and is a serious competitor to the HTC One M9.
For me, a flagship phone needs to hit a lot of marks to be considered impressive: it has to have cutting-edge performance, beautiful design, a powerful camera, long battery life and not be too hard on the pocket.
In 2014 HTC hit nearly all these marks, with the One M8 excelling in every area. OK, it wasn't cheap, but nor was it the most expensive on the market. It didn't have the best camera, but it was the most innovative.
One year on, HTC didn't find itself at the top of any of those categories apart from design, where it still showed the rest of the market how it should be done. It raised the price by nearly 8% and yet didn't deliver any discernible upgrades beyond a more mature camera and slightly more professional speakers. It's all nuanced tweaks, not powerful improvements.
Of course, the HTC One M9 is no longer HTC's flagship phone, so can't be held to the same exacting standards. But it now finds itself competing against a new breed of capable mid-rangers with, in many ways, superior components.
I think I'm most disappointed by the camera used here. I was expected HTC to come out all guns blazing, showing us that it really did believe the megapixel myth was something to be fought, that lower MP counts really do count for something.
Instead of the next generation of duo camera, an 8MP UltraPixel sensor or similar, it seems to have thrown in the towel and decided to try and make more megapixels work… you know, just like everyone else.
This is a phone that has all the DNA of the HTC One M8 and polishes it well. Theme creator adds a lot of personalization to create an emotional attachment with the phone, and the Sense Home widget seems to be really useful too.
I thought I'd be getting rid of it straight away as I've seen this tried over and over again by other brands, but it's actually useful and surfaces the best stuff at the right time.
The main thing I liked is the design though. It was easily the best on the market at the time, feeling almost hand-crafted with a great aesthetic and great feeling in the hand, and it still feels great even now that the HTC 10 is on the market.
And while things like BoomSound, BlinkFeed and Sense haven't necessarily been improved much, they're still really great features that HTC is rightly proud of, showing it's still a market leading brand.
Sadly, there's more to criticize in the HTC One M9 than there was in the previous couple of years. The first is the battery: I would expect strong power management from a 2015 flagship, as shown by most of the One M9's contemporaries, and instead I got something that was a step backwards.
That's a reduction in power with no discernible reason either – the full HD screen isn't any different from last year, the battery is bigger and the software presumably stable - especially now that it's on Android Marshmallow. So why on earth are we not seeing at least 36 hours of battery life where I'm not even getting a day?
The camera is more powerful than I was expecting but I'm still disappointed in the loss of the UltraPixel and duo camera combo. I wanted to see an 8MP advance on the One M8, maintaining the strong snapping speed, and instead I got a sensor with the same specs as the one Sony had been pushing for over a year at launch – although it does take some great pics on occasion.
The biggest issue I have with the One M9 is that it doesn't impress me as other models have. Good design is fine, but it seems like HTC's just remade the phone from 2014 as it didn't have anything new to add into the mix. Taking the DNA from the One M7 and One M8 doesn't mean that's fine for a new handset.
Let me make one thing clear: the HTC One M9 is an excellent phone, filled to the brim with good features, a clever interface and a design that it should rightly be proud of, once again showing every other brand how it should be done.
The issue is that it doesn't improve enough. The One M8 was pretty much the perfect phone, and not much has changed year on year… in fact, HTC has gone backwards on battery life and hasn't really done much more than polish throughout the phone.
Except perhaps in the camera, where things are improved and needed to be given that was somewhere HTC was struggling to gain consumer support. It's now just the same experience as on every other phone though, and I miss last year's innovation.
HTC hasn't been as arrogant as Apple by simply bringing out an S version of its phone though – there are some genuine upgrades, which are evident the second you put the One M9 in the hand. It makes the design of the M8 look sloppy in comparison, for instance.
This is a phone sold on precision, but comes with far too many ragged edges to be considered worthy of a perfect score again.
It's all tweaks and polish, an admission that HTC managed to create something brilliant in the One M7 and M8 and was loathe to deviate too far from that formula. Which is a shame, as this is a brand I've almost come to rely upon to offer genuinely useful innovation time and again.
HTC might not have quite lived up to that ideal in 2016 with the HTC 10 either, but at least it created something new and consistently strong. In its predecessor we got a good phone - a pretty darn good one - but not brilliant.