Turtles In Time: Re-Shelled is an example of what could have been.
It is, as I mentioned, a remake of the original Turtles In Time arcade game from Konami. While the graphics look fine, it would have been nice to have the option to play the original as is. The gameplay is a simple and straight-forward hack n' slash type of game, and it does become a bit of a chore after awhile of play.
Online multiplayer works fine. It is fun to play with three other players, but if you have beaten the game that way as I have, there might not be a reason to return to play the entire game in single player mode.
Overall, TMNT Turtles In Time: Re-Shelled looked promising, but after you beat the game, you might not have any more interest in playing it through again, even for the achievements you didn't obtain the first time. You might as well play the first TMNT game that is currently available on XBLA for half of what you are paying for this game.