Funny enough I've literally (yesterday infact) just gone from using an Iphone 3G to using a Galaxy.
So far I've been able to find android Apps for most of the things I had on the iphone, (In some cases much better ones)
The iphone has a brilliant UI, probably one of the best smartphone UI's I've used and it's web browser is also pretty good for a mobile browser, love the multitouch zooming.etc
BUT and there is a But the inability to background an app without resorting to hacking the phone was driving me nuts, particularly as I recently became a subscriber to spotify and use it to listen to music on my commute to work.
Becuase I wasn't using the built in "ipod" to play music it would mean I could Listen to the music OR check my email OR browse the web...
It gets irritating very fast when you to have to pause a song so you can see an email that's just dropped into your inbox.
I also hate the idea that Apple lock down the platform so much that all apps have to be pre-approved and unless you hack the thing.
I found the Android UI to be fairly easy to learn and the ablity to background the apps is a godsend, now I can if I wish listen to spotify AND browse the web
Also I recently switched from using a hosted exchange provider to google apps (save some cash) so the tight Google integration was one of the other reasons i went for an Android phone.
Now all I need is a decent RSS reader that can pull from google Feeds (I used netnewswire on the iphone, and feedly on the pc) and i'm happy.
All in All I'm pleased with the phone, seems to do everything I want, not really had it long enough to comment on the battery life, but then again I was often only getting a day out of the iphone.