I had a Samsung Vibrant. Really nice phone, lots of cool stuff to do on it but the battery life was absolutely horrid. I didn't really use the phone to it's "full potential" and it's lack of keyboard and battery life just became a little too much. I gave it to my girl and got a Blackberry which I'm much happier with. The Android operating system is really nice, lots of awesome apps but I find the nicer Android phones all seem to lack keyboards and die after about an hour of usage. They're great phones for people who like to play games and check out a lot of (for the most part) expendable apps.
I'd honestly recommend a Blackberry if you're looking for a good smart phone. Easier internet usage, better battery life and a keyboard.