Motion-sensor technology is something that we've wanted for the home console for a long time. There are a handful of games in arcades that use it, and some of them are very fun and interactive. However, these games have problems, and they are very present in the Wii.
I've had my first real contact with the wii last night, and while I'd have to play much more to see a real verdict (mainly single-player parts of it, as I was playing group games), my initial thoughts are not good. I should note this is the newer version of the controllers with the upgraded sensors.
The first problem was the sensitivity of the controller for menus and the like was too fine. This made it hard to use the keyboard to make a Mii. This is a minor inconvenience, but it also meant that during a game, sometimes very weird things would happen. The controllers also have a strange disconnect problem where they will stop functioning for a few moments until they are set down and remain still.
The second problem is that the games themselves (for wii sports and sports resort) are poorly designed. Bowling worked fairly well, but the swordfighting game had no real strategy to it besides flailing randomly. Defending works once, but if you get hit once and your opponent is just flailing at you, you will get knocked off with no chance to recover. The air sports fighting game is pointless as well. Most of the balloon tokens you can get to are spread far enough around that they are hard to get to in time, and the whole game takes place too close to the ground for any real maneuvering. It is a game that is a good concept, but poorly implemented. These designs have me question the potential for the console and the various swordfighting and jedi games we'd like to see for it.
Finally there is a limited range arc in front of the sensor that the remotes are active in. Because of this, playing with four players in anything but a clear room results in potential injury. Even with two people playing there was plenty of chance for injury.
On thing I really like is that multiple players can use one controller in some games. This is much easier than playing a two player game and taking turns with the controllers.
Overall I'll need more Wii time before I can decide if I like the console or not. Its not looking good for Nintendo's motion sensor baby.