I switched from my 3GS to the Droid.
I had the iPhone-iPhone 3G- and as stated, iPhone 3GS.
Never ever going back to AT&T's horrible horrible service even though I did like the iPhone but the Droid is just the same, if not better than it.
That's how I feel. I got a Droid last week for my work phone. Loved it so much marched myself down to Verizon today and purchased one to replace my iPhone 3GS. It feels amazing to be able to talk without dropping calls, and I love the voice clarity on the calls I do make too. As far as the phone itself I find it just as capable as my iPhone. Since I'm a bit of a tech nerd, I'm having all sorts of fun customizing the phone to my liking. I felt customization was always lacking on the iPhone. The media player was better on the iPhone but apparently there are some pretty darn good media players in the android market that are better than the stock version.
I'm curious to see what 4.0 will bring however I'm quickly becoming a Verizon fanboy. I feel so much better being able to actually use my phone as a phone! Chances are I'll never be back to AT&T unless they are able to bring their 4G network to our area and it's as reliable as Verizon is today.