It's not the new font, or icons, or apps, and it's certainly not the homescreen parallax effect. It's something simple that you'll use all the time.
When you're at home, you want the Wi-Fi on your phone to be turned on. It saves battery life; it loads, downloads, and sends things faster; it keeps your data use under control; and sometimes it's the only way to do high-bandwidth tasks like downloading huge apps, games, magazines, or videos.
Then, when you leave the house, you turn it off, because you don't want your phone constantly searching for a Wi-Fi connection that may never come. This wastes battery life. Also depending on your settings it might be annoying. Here's how that's done on the iPhone, right now:
1. Hit the home button to exit out of whatever app you're using. 2. Navigate to the page of your homescreen on which your "Settings" app lives. 3. Open Settings. 4. Hit the "Wi-Fi" setting. 5. Switch the Wi-Fi setting to on or off, and select your network if necessary. 6. Double-click the home button, tap the icon of the app you were using to go back to where you were before this whole mess started.
This is dumb! So we were very pleased to see that Apple, at today's WWDC event, announced what they're calling the "Control Center." Whatever you're doing, in any app, swipe up from the bottom of your screen. There you'll be presented with all the toggles and switches you'd ever need: Airplane Mode, Wi-Fi, Bluetooth, Brightness, Rotation Lock, Night Mode, AirPlay, Play/Pause/FF/RW/Seek controls for music, and even basic tools like a calculator, flashlight, and camera. When you're done toggling or switching or adjusting, swipe the Control Center right back down to the bottom of the screen, from whence it came.
This was starting to get embarrassing; Android has had the ability to quickly adjust settings for literally years now, and this kind of very simple tweak that makes users' lives easier is exactly the kind of thing Apple should have been great at from the start. So, there it is: Control Center, the best thing Apple announced today.