Here's what i think would made this game, and it's predecessors, a whole lot better.
First off, since the game kinda feels like the 'X-Men Legend' games to a certain point. So it would've helped if single players could control all four Turtles by selecting them with the d-pad. As well as playing the others once the one you were playing loses all it's health, and dies. Having to play as one Turtle, and having the game end with just one Turtle dying off seems unfair.
Yea, I recently tried this out and you should definitely be able to switch between turtles during the game, at least during the main beat-em-up action levels. You can tell they borrowed heavily from that game, so it was an odd ommission. I also thought the enemy variety could have been a lot better. Overall, the game just feels rather cheaply made. It is still fun, but it fails to really captalize on the license in any area. It often goes for over $15 too, so unless you are a big fan I'd skip it.
Oh and I unlocked TMNT In Time for the arcade and I was disappointed to find out that it plays choppy, some graphic/sound effects are missing and the music is completely changes the music. It just feels weird with the new tunes blaring. I don't know why they changed it. Still, it is the best you can get for a home version of the arcade game. There is an XBL game but it is a remake with new graphics. The SNES port is still the best, but I'm glad I have the arcade game now in some capacity.