I did not notice much change on the Iphone 3GS compared to the 3G one, both appears to be working fast (I did not run any intense applications though, if they even exist?)
The video sucks, the camera sucks, at least on the 3G model only the camera sucked since video was not supported
The best camera I had in a phone was in my old nokia n90, if the camera is important you are probably better off looking for a different phone
The good thing about the 3GS over the 3G is that it is really easy to jailbreak the phone to install "unapproved" applications