I’ve got a 3G (not 3GS) which is now over 2 years old. No issues with it, although I did smash the screen (£60 to replace) and I had to superglue the vibrate button back on the other day. Still works though!
It’s not as fast as the 4G I had for work, but I’ll hold onto it a bit longer until I have the money to burn on a 4G.
AppleCare wouldn’t cover things like dropping it in the sink, smashing the screen etc, but one “fault” repair and it has paid for itself. I haven’t bothered with AppleCare though. I’m trying to spend as little money as possible on it, and if it falls apart sufficiently, I’ve saved some money towards the replacement.