Animal Crossing: City Folk is a sloppy, lazy port of a Nintendo DS title to the Wii. It's everything that everyone hates about Nintendo – overly safe and underdeveloped, and it misses every opportunity it has to be a killer app. That doesn't mean it isn't an incredibly fun game for fans of the series, but it does very little to add to the already established formula.
The game will likely sell regardless of the lack of improvements due to the obscene amount of shovelware on the system, but with some more effort on Nintendo's part, the game could have been a real holiday blockbuster. Their apathy towards the series and complacency with their current success stunted the title, stopping it from reaching the heights it could have reached.