I have been a big iPhone fan for the past 3 years, but have just swapped over to a HTC Desire with Android 2.1, after the iOS4.0 completely ruined my iPhone (slow, freezing up, rebooting).
It is soooooooooo much better than iPhone! Can do so much more, its a lot quicker, pretty much everything I've done on it so far beats iPhone by a mile. There arent quite as many good apps, but I have everything I used on the iPhone on it, or an alternative. The Android market is also a lot more user friendly than App Store.
Maps are much better, Google directions, Google Buzz, etc etc.
I think I have only just realised how much basic stuff Apple stop you doing on the iPhone.
(video contains bad language)...
http://www.youtube.com/watch?v=FL7yD-0pqZg&feature=related