Performance on the 770 is decent. It is a mobile device so I am a little more forgiving then some on it's computing power. For the most part it performs very well for what it was designed to do.

Battery life is excellent. MUCH better then I expected. Range in also excellent, again, MUCH better then expected. It actually will pick up WiFi signals my laptops don't see. I haven't had issues with the screen. I do not have a screen protector on it and have no scratches. It comes with a slide case which helps a lot when you put it in you pocket or bag.

I don't have a lot of experience with a lot of other portables minus Apple products which at this point I shy away from but that's another thread. Overall it does everything I want a portable device to do, music, movies, WiFi, IM. The browser experience is the best experience I've had with any portable device. Note: it does not do well with some Flash and Java which means YouTube is out, but for me that is OK.

Sorry for the jumbled mess above. I am in a rush as we all are.