Controls would probably be well implemented, most everything else would fall on its face. Versus mode simply would not work for local play... at all. Since Left 4 dead completely fails at being a good or engaging experience when played alone, a Wii game that *requires* online to get a good experience would be a tough sell indeed. Having to add people (friend codes) to play online would add a layer of annoyance, while simultaneously removing the ability to jump online for a quick game. The only way this could work on the Wii would be 4 player local.
Demon's Souls Official Thread | Currently playing: Left 4 Dead 2, LittleBigPlanet 2, Magicka