I think it's the first Mario Kart where the vs. mode is the most fun. I think that's a good thing because that's where most of the tracks are. In every other Mario Kart my firends never want to play vs, but in this one, no one ever wants to play battle. I thought shine theif was pretty fun, and never got to play a game of the bob-omb mode. Normal battle is not terrible, but not too great either.
I like single player mode, and the 16 track circuit, but the computer cheeses so goddamn much that it's a HUGE turnoff. As soon as I get into 1st place I get whacked with a blue shell. Every fucking time, like clockwork.
I kinda hate Co-op mode, because if I'm in the back, it's boring because my partner never powerslides. There's not much cooperation going on, one guy usually just drives for the whole circuit.
Overall, it's fun for multiplayer. The game helps whoever is losing more than any other Mario Kart.