On the left is April 10, on the right is April 8 (April 3 is below)
Fun story about the HTC One X battery life. I've seen it be one of the worst performers (thanks to a since-squashed server-side bug), and I've seen it be one of the best. In addition to reviewing phones, we often end up as guinea pigs, using hardware that's barely had time to let the glue dry, or software that's not quite final. In the case of the HTC One X, it's been both. The hardware is solid. I've got no concerns about that, save for maybe scratching the camera lens.
The software we're running on our review unit actually is a tick above that of the retail units. I'm not sure if that's causing some disparity. But more than that, my usage case is going to be different than yours. My network is different than yours. I am not a normal user.
That said, I've been pretty impressed with what I'm seeing after three weeks of use.
When I'm at home, working, I'm on Wifi. And that's for a good chunk of the day. Not every day, though. So when I'm running around town, chasing after the kids or doing errands, I've been on AT&T. I'm pretty heavy on Twitter (and I'm back on Seesmic, since it finally updated for the HTC One X), Facebook and Google+ throughout the day. Browsing, too. And because the One X has that excellent camera, I've been taking more than my fair share of pictures (which I've got auto uploading to Google+ when I'm on Wifi).
So there's your macro view of how I roll. And I'm getting well over 12 hours of use between charges. Hell, I'm getting well over 15 hours on a single charge. It's a little ridiculous when I stop to think about it, and it makes me want to pick up the phone and use it some more.
We're going to have to see how this changes once we get the AT&T version of the One X here in the states. For one thing, it'll be using the dual-core Qualcomm S4 processor instead of NVIDIA's Tegra 3. For another, it'll have LTE data in some locales, and presumably it'll have some fine-tuning for AT&T that this European GSM version won't (though they do share the same radio frequencies, so maybe that'll just be in our heads).
That doesn't change the fact that when the One X battery is drained, you'll be needing a charger. No swapping batteries. So keep that in mind. But once we get it on AT&T, it'll be an interesting experiment, to be sure.