It depends entirely on whether the games that are available now are things that interest you.
In my opinion, the best launch games are:
Zelda: Twilight Princess
Rayman Raving Rabids
Super Monkey Ball
Trauma Center
(Apparently Madden is pretty good as well, but I don't like sports games)
These games are pretty good, but they exist in better forms on other systems:
Call of Duty 3
Marvel Ultimate Alliance
The other games include licensed crap (Cars, Happy Feet, etc) and mediocre original games (Red Steel, Excite Truck, etc).
Also don't forget about the Virtual Console, which is one of the big draws of the Wii, even though the games that most people are waiting for aren't available yet.
There are ALWAYS going to be more good games out 6 months to a year after a console launch. The question you should ask is, does the Wii have enough available now to justify the purchase? Remember that you can get Zelda for the Gamecube if you just want Zelda.