Accessible controls so you can play against your noob friend/family and they have at least a chance of winning. Huge depth, ever after years of playing I'm still refining my style.
Not only a great variety of characters but each character is totally unique (with a few semi-clones).
It's fun, pure fun.
You can tailor it. Don't like an item? Leave it out. Don't care for some levels? Leave them out.
I'd like customizable Miis added.