Same here, through Sprint.
Wifi, trackpad, and more memory...
Trackball jammed up a few times, and while easy enough to fix on your own, the trackpad doesn't jam at all.
Did I mention Wifi? I live in the boonies in upstate NY, and my 3G signal is hit or miss. With Wifi, I might not be able to make crystal clear phonecalls, but I can get on the internet.