I have played Wii Sports, Wii Fit, Excite Truck, Twilight Princess. Everything for hours.
I expected Sports would be intuitive, but it was anything but. The input scheme was not responsive, nothing like doing the things IRL, and it was also not as clear as regular videogame controls. The result is that you have to learn a new, additional layer of obfuscation which didn't exist previously. It's hard to imagine something more frustrating to a gamer than obfuscated, sloppy controls. I'm afraid a lot of the "newcomer" attraction to the console might be based on that the controls turn a lot of the game into luck, meaning the player is not responsible for their win or loss.
Overall verdict: meh. None of the games I played even come close to warranting buying the console. I'd like to try Trauma Center, Metroid Prime 3, SMG and maybe some titles region-locked to the Japanese Wii, but that's about it. For someone who hasn't played them on previous consoles, Okami and RE4 would be good buys. I hear Okami and RE4 got good ports, but that's hardly relevant to someone who has played them already.