A game not to play alone.
Graphically, the game is not that great, the 2D concept is a tad strange, it took me a while to really understand what Mario was driving. The courses do have their own little things, but I can't say that they stand out, some do, but right now I couldn't say what they all look like.
The controls are easy, there isn't much thought out on the driving, it's really just who presses A the longest and who doesn't get shot by turtle shells that wins. The characters have some differences, but it's barely noticeable on some, you can notice the difference between Bowser and Toad, but could you notice them between Mario and Luigi ?
Now, as I've said, playing alone is fun at the beginning, but you easily finish it and get tired of playing it. With friends it's a different story, you'll find yourself having much more fun competing against them. The multiplayer mode is also quite entertaining with the battles.
But frankly, the game grows old and I think Nintendo should have put a little more effort in it.