I've now played Mario Kart Wii with my brother-in-law, my wife, my wife's classmate, a friend in Tulsa, my best friend, my mom, and my dad.
It's a great multiplayer game, though it has its flaws and quirks (as does any title). I admit it's annoying to drop from 1st to 6th just because I got hit by a blue shell, but one can't have fun with Mario Kart if one takes it too seriously.