One of the best racing games of all time!
On the negative side of things, I have a few. Beating staff ghosts to unlock expert ghosts is extremely hard to do. Also, steering with the Wii Wheel can sometimes be hard. The one thing that is really frustrating is the 150cc races. It is almost impossible to win a single race on this difficulty. The amount of times that I've been hit by a red shell, gotten back up, then been leveled by a Bullet Bill or a Star racer, gotten back up and then got drilled by another red shell is infuriating. It's also hard getting the items you need when you're in 6 or 7 place. Usually i get three mushrooms, which will maybe get me in 4th. Gee thanks.
All in all though, Mario Kart Wii is one of the best games for the Wii. If you don't have it in your collection, you better go get it!