As mentioned above, the planes were good, the hovercrafts were bad, and they balance out in the end. That the variety existed at all was a point in its favour.
The power-ups were perfectly tailored to a single-player mode, but they removed all fun from the multiplayer. The randomness of Mario Kart is often complained about, but it's the reason that multiplayer games are always close and tense rather than "I-know-every-turn-in-the-course-therefore-I-win".
I use games to relax because I think hard enough in everyday life! Anyway, remembering the layouts of 20 courses doesn't make it "the thinking man's game": neither required that much intelligence, just memory. But if you're going to insult my choice of pictures, I have no choice but to bring out the big guy:
WHERE IS YOUR T.T. NOW?