It's Animal Crossing, and nothing but.
Animal Crossing: City Folk has it's good points, like the town and new Wi-Fi, but besides that, nothing is really that all different. They even took things out of the game, which really kills it.
The game just overall is Animal Crossing GC all over again. If you haven't played Animal Crossing before, I'd suggest buying the DS version. It's portable. Perhaps if you're a cheater but don't have an Action Replay, the Gamecube version.
Things added in AC:CF won't really make a difference, unless you want the auction house and Gracie Grace (expensive).
This is just another series Nintendo needs to kill off now, or at least not make a fourth.
This has been Asiancat, catch 'ya next time. :D