Very fun game. It's kart racing action and a free for all in one game improving off of previous Mario Kart games.
You chose Nintendo characters like Mario, Luigi, Donkey Kong, Bowser and many more. The gameplay is as expected since previous Mario Kart games. It is a free for all. Shells, power stars, bannana peels and many other power-ups are available during the race. You can also choose to pick motorbikes instead of Karts which is a nice change from the games original formula. You can use the Wii Remote with a steering wheel attachment. This is very fun but takes a while to get used to. You can also use the gamecube controller, but I feel it makes the game too easy.
Most tracks are new and some are remakes of older ones from the GBA, DS, Gamecube and N64.
As you race, on the 50 cc, 100 cc and 150 cc circuits you unlock new bikes, karts and characters. Each vehicle in this game has different attributes so it's not all the same. You can also play battle, which is the classic balloon battle where you have 3 ballons, each one represents how many hits you can withstand. Once they run out, you lose. There is also a coin battle, in this you collect coins in the race. Whoever has the most coins at the end wins.
Online is standard, race or battle other people all over the world. I will say that there are some mod'ers and this gets irritating, but there isnt much lag if at all during races. It doesnt take long to get into a game either.
One thing I didnt like is the overuse of the lightning powerup and the Blue Shell powerup. These two powerups literally screw you over way too much, and happen too often for how powerful they are.
All in all this is a very good game, fun, addicting and has great replay value. The CPU will give you a decent challenge but online is where this game may excel. There is nothing more fun than playing other people. If you ahve a Wii this is a must have game. It has some nastalgic moments as it recaptures older maps, and the new levels are fun and never seem to get on your nerves.