Their description:
Product Description
The Nokia 5800 US 3G XpressMusic is a S60 5th Edition device with a resistive touch screen and tactile feedback. The device has a large 3,2 inch, bright nHD (640 x 360 pixels and 16:9 aspect ratio) color display. The device has variety of input methods: stylus, plectrum and finger touch support for text input and UI control (alphanumeric keypad, full and mini qwerty keyboard, handwriting recognition). Use the Nokia 5800 US 3G XpressMusic to connect to mobile broadba… More >>
Go & get it here - i can recommend it:
Nokia 5800 Navigation Edition Unlocked Phone with Free Voice Navigation and Nokia Navigation Accessory Kit–U.S. Version with Full Warranty

3G does not work with T-mobile’s network! So, that leaves only one big network - AT and T.
How different is this from a AT&T branded phone then?
This phone looks great and the system works fine but the touch screen is horrible. I wouldn’t recommend this phone to anyone. I try using it for a couple of days and I got really annoyed using it. The phone feels cheap and the “unlock button” is in a very inconvenience spot and every time you want to unlock it you have to slide it down, which by the way it also feels really cheap. For the price I don’t think this phone is worth it.
I bought this phone from Amazon, and it worked fine when it arrived. However, it shut down the next morning, and it does not start again. All of the numbers provided with Nokia are either (1) busy permanently or (2) all about asking you 10 annoying personal questions without understanding your problem, and then hanging up the phone. Please NEVER buy a Nokia product in the US.
My 5800’s touch screen doesn`t work well. It’s too slow and stupid. I have to touch it many many times, and it doesn’t work. I just recrived it this afternoon.I don’t know why,only my cell phone have this problem?