I rented this game and must say it is not that great.
It's shallow, the moves are boring, and frankly there is not enough variety in stages or characters.
It's clearly meant to be a Smash Brothers clone as it is the same developers (Game Arts) yet it has absolutely no soul.
I then took the the game out after playing multiplayer with my wife and some friends (all hated it), and the arcade mode, and the missions. All of it was boring and I love the original black&white comics, later cartoons, and even the live-action movies. I put Super Smash Brothers in for the first time in six months and was just blown away how good it is in comparison. Every character plays tight and has gazillions of moves etc.
TMNT's biggest flaw is that the move-sets are really limited and boring.