It also works fine on Windows Mobile phones like the HTC TyTN. The TyTN does support HSDPA and is noticeably faster... But I've stuck with the iPhone because even though it has its drawbacks (no 3G, lack of real keyboard, etc.), I prefer its slimmer size and the web browser is excellent overall IMO.
[edited by: Rehan at 2:36 am (utc) on Feb. 21, 2008]