I have an HTC One, moved from an iPhone.
Really well made, nice solid device, fits my hand perfectly. I bought a case and screen protector immediately, always do with a new phone.
I’m very impressed with it. Sound is excellent, good as a phone. The camera is a bit poor in low light but otherwise it’s great. The screen is big enough to watch films on comfortably as well as reading books.
Poor points? Battery life isn’t great. If I turn off wireless and 3G when I’m not using them as well as putting the screen on half light then it’ll last me 24 hours, maybe longer. Likewise GPS. Getting an app that provides a toolbar to do this really helps.
It’s lightning quick, never seen it stutter with anything. Recommended.