Online is a big focus for Mario Kart Wii, and it's about as good an implementation as possible within Nintendo's labyrinthine rules and regulations for Wii online play. The racing itself works well, and the Mario Kart channel has all sorts of goodies to allow you to view the statistics of players worldwide and find your place on the bell curve of Mario Kart skills.
Game Informer feel very strongly that dropping the tag-team racing from Double Dash was an utterly boneheaded decision on Nintendo's part, but you can't fault much of anything else in Mario Kart Wii. This is a great game, single- or multiplayer, online or off.
