I still have the 3GS and I love it (though I do want to upgrade).

I'm not sure if they still have a 1-year automatic warranty, but the modem (? whatever senses the data network) went out in my first one. I walked in to the apple store, they ran some tests on it, and went to the back and got me a brand new phone. As soon as I got home I synched it and voila! everything was normal again.

The only complaint I have is that I dropped the phone and broke the "silent" switch on the side, so there is no way to turn the sound off entirely anymore. I wish there was a backup way to do that without the switch, but oh well.