Super Mario Kart is a weird game in all of Nintendo games. Pretty much every Nintendo game, especially from the SNES on would be classified as pretty easy. However, Super Mario Kart goes above and beyond to show how much of a dickwad Nintendo is.
The AI will only use their weapons when you are close to them, or infront of them. The AI will purposedly ram you, and even if you are Bowser, Toad will knock your ass around like nothing. Playing all the other Mario Kart games, and then playing this one, it's like some other company made it. It's one of the hardest Nintendo games I've ever played, especially when you get up into 100cc and dear god at 150cc.
The courses are really short, but just long enough to have them rip you a new asshole.