I had a wii for 3 years, then a PS3, and about to buy a 360
I had Call of Duty: World at War on Wii and thought it was AMAZING, not too addicting like MW2 on PS3, and not too boring. It was perfect! I recommend buying a gun accessory though, here are the 2 I had.
I had this... http://www.gamestop.com/Catalog/ProductDetails.aspx?product_id=68825
The Wii Perfect shot, but I would NOT recommend it. Broke on second day, and didn't respond to movement well.
I then got this... http://www.gamestop.com/Catalog/ProductDetails.aspx?product_id=67154
The Wii Zapper (comes with Link Adventure game) and would recommend the most, because it is so much fun to use and hold because it is a gun shaped item. I would buy this. You can go into the settings and change your button layout and the button layout is designed for this accessory. This is really fun to use.
t will be really fun to play on Wii, I still enjoy doing it now, just buy it and don't regret it