I have an HTC One X - the predecessor of the new One.
It is a superb phone.
The OS is very easy to use.
Battery life is about 24hrs with fairly normal usage e.g. a couple of hours of calls, 30mins as a hotspot, bit of GTAIII, email, facebook, newsreading and texting.
Turning the WiFi and Data connections off makes a huge difference to battery life, pushing it into 3 days fairly comfortably.
If I could have a do-over, I'd have bought a Google Nexus 4 (since I now have a Nexus 10), but that is purely because Google's UI is more intuitive than the HTC (which is still extremely good).
People say iPhones 'just work', but I've had an iPhone and this HTC - both of them 'just work' except one of them doesn't muck about with iTunes and a bizarre file structure that makes it really hard to explore on a computer.
Using a mini-micro USB adaptor, I can also explore my camera's memory card on the phone (or tablet) and pick photos to upload there and then, or copy for uploading later, or delete some that look odd when shown on a proper screen.
The keypad is nicer than the iPhone's IMO.