Disclaimer: I work for Microsoft and have to admit I'm a big Xbox 360 fanboy so I will not be fully objective on this topic.
Ever since Nintendo has annouced their new controller, I've had very big doubts about betting the console on such a concept. The controller in itself seems to be beautifully executed and more precise than any other previous attempt at a motion-sensing controller, but I fully agree with Peter Molyneux that for most players, the most confortable position to play is lying on the couch with the controller resting on the beer belly. Only the thumbs move, and they do so very little, which enables us to play for extended periods of time (not that we *should* play that long, but we do, and that eventually makes us buy more games). And I call that motion sensing too: the pad is very efficiently detecting very small movements of my thumbs...
If I have to be in an upright position and wave my arms around to play, I can assure you that I won't play for more than 20 minutes to half an hour. The Wii controller will certainly work beautifully for a tennis game, or a golf game, or a sword fight game, and you can trust Nintendo to be just as creative with that as they've been with the DS touch screen (why we weren't smart enough to do this kind of games on Pocket PCs years ago and why we're still not doing them is beyond me). Still, I prefer to do my sports outside. Video games, for me, will stay in the couch, mostly not moving for hours. That will make me buy more games, a Wii wouldn't.
So when I saw the PS3 controller, after the initial shock - or lack thereof - (motion sensing? no, they didn't? hey, what's the big round button in the middle of the controller?), I thought that they had actually been pretty smart about the whole thing: their controller will be perfectly fine for any game, even though it won't come back when thrown and it will be somewhat less ergonomic for tennis games than the Wii controller. Then again, the tilting pad was tried before, including by Microsoft. I still have a FreeStyle somewhere in my closet and it was excellent at Motocross Madness and racing games in general (because we already tend to move with the pad in this kind of game) but terrible at almost anything else. So is this just Sony going "me too"? You decide.
But wait a minute... Didn't Sony already have a few PS2 games (mainly sports) that were controlled by the player's body movements? Well, yeah, and by a strange coincidence, the kind of games that work with the Eye Toy is exactly what the first batch of Wii games will be. Come to think about it, this is probably the most sensible approach (and it seems to be the XBox team's approach too).
Another powerful idea is that what seems like such an obvious control scheme may not be as efficient as your intuition will tell you. Here's an interesting comparison... When you think about FPSs and how the keyboard+mouse combination is the absolute best control scheme for them (even though the devices themselves were created for something entirely different), it's just mind boggling because it's so non-obvious. You'd think that detecting eye movement for example would work better for aiming in such games. Well, it doesn't. As a recent study showed, it is less efficient by 25% and just less enjoyable in general. Maybe that's because eye movement is widely unconscious whereas the eye-hand coordination is something that works really well in human beings.
I really like the idea that one controller can't be perfect for all games but that the default controller should be versatile enough to be ok for all games. I've owned a force feedback wheel for the PC for years and it just makes racing games much more immersive; I own a big joystick for flight simulation; an arcade stick will be better for Street Fighter and Pac-Man; mouse and keyboard work best for FPSs. In the same way, the camera will provide motion sensing for those games where it makes sense. But all of these games can be played with a regular controller without a problem, it's just that a special optional controller can make the experience better. The Wii controller just seems perfect for a very small number of games and terrible for everything else. In my opinion, it should be an option because it's just not versatile enough.
UPDATE: the reports from the first people to play with the console for extended periods of time are starting to come in, and it seems like the Wii, like a Gyration mouse, does not necessarily require big movements and can be enjoyed for long periods of time. Well done then. What still needs to be determined is how well the controller will work with "ordinary" games.
UPDATE 3: Penny Arcade on the Wiimote.
UPDATE 4: I just read Ars Technica's review of the Wii and they have very good things to say about the system. In particular, "I found the nunchuk + Wiimote combination to be incredibly comfortable in long playing sessions. I was able to rest my hands on either side of my legs while playing Zelda, and that wouldn't be possible with a classic controller design" struck a chord with me. Again, I'm ready to be proven wrong and will gladly admit I was wrong. After all, the DS stylus gaming has been dimissed by some as a gimmick when it was introduced, but it has been working absolutely flawlessly. I'm a big fan of the DS (I have both the phat and the light models), it works perfectly for me, my wife and my three year old daughter who is addicted to Nintendogs. It just leaves me wondering why we didn't get games like those on PocketPCs years ago and why they're still nowhere to be found. If the games deliver on the Wii like they did on the DS, I'm sold, I'll get one and I suppose I'll buy Mario and Zelda. Again. And again. I'll try the Wii at fwends' house and make a first hand opinion soon.
UPDATE 5: Joystiq made a *very* interesting (although unscientific) poll of their readership that kinda confirms the title of this post: