I don't see why you're complaining that much. All levels fit well with the style of the mod, and most of them play okay. The items are quite well done, even though they're pretty useless sometimes, and one of the weakest weapons(banana) is now one of the strongest weapons. The characters are well done, but I really dislike Naruto in a kart game.
The SOC...well, I'm both very positive as negative about it. It makes for a interesting effect. You can't jump, nor move, so it really feels like you're using the gas pedal. I dunno if its a bug or something intended, but you can go really fast and uncontrollable if you land after a spring or jump and directly press the spin button. Its a really handy trick, and its quite balanced too, considering you have to stand still before regaining normal control, and because you're hard to control while going that fast.
As side effect, getting hit by your own weapons kinda sucks, as well as that this SOC totally ruins Sonic and friends' jump and spin control. I know that jumping makes you go fast, and thats a bug, but you should've used nojumpspin to avoid that. In the regular Mario Kart games, you can make a tiny jump, too, ya know?