There's no classic or Gamecube controller support. There are still times where the game will give you an instruction on how to perform certain tasks, but it'll be for the Gamecube version of the game ("Press R to do X", even though there is no R button on the Wiimote or Nunchuck.
They've added motion, like most games on the Wii, but it's just thrown in. You can alternately use the Z button instead (which is preferable).
You can't play as the girl, you there goes that option....
There's a few more bugs and script errors, but you probably won't notice.
Other than those, the game is mostly identical to the GC version. You're better off buying the Gamecube version, which is cheaper, has more options, you can use a better controller for it, but if the Wii version is the only version that you can get, then go ahead and get it. It's still a good game, and a pretty darn good port.
Praise Rainbow Mika SSBB: 3652-6261-7096 + Mario Kart Wii: 2707-7247-9079 + Samurai Warriors 3: 0346-6035-0276