I played with it for a bit in store. Max of 6.5mbps down and 1mbps up in Denver. Pretty quick and smooth screen switching and app launching. 1.95gb free for apps internal storage, which is a lot.
The security cables wouldn't let me close the keyboard so I couldn't really see how thin it really was but seems that it wouldn't bulge in Jeans pockets. 4" is a great size IMO.
Great phone but for the same price I would get the high end gs2