Galford is right, the Wii remote is not very friendly to certain types of games. That's why the classic controller exists. Just like arcade controllers exist for people who really want that authentic fighting game feel. And Joysticks exist for people who won't play flight sims any other way. And instruments exist for music games. And that huge-arse control console exists for Xbox fans that want a more immersive Mech game.
However, the argument from Nintendo's end is that this is going to become the new standard, just like the NES pad replaced Joysticks 20 years ago, and analog practically replaced the d-pad 10 years ago.
Is Nintendo right? Maybe, maybe not. Many previews have surprisingly praised the controller in Marvel: Ultimate Alliance, in spite of the fact that it's a very traditional style of game. Racing games, Rayman, and Madden have also all gotten good previews. FPS's are having trouble, but IGN's last Metroid Prime 3 preview was really positive - maybe it doesn't beat a keyboard and a mouse, but if it can beat old-fashioned controllers, that's a start. If one or two genres fall by the wayside but it provides a better experience overall (and especially for "non" games) then it won't matter except to some hardcores...who, once again, can buy the classic controller.