It's simple, to the point, and best of all, captures the essence of the classic Turtles arcade games.
One important thing to note is that this is not a sweeping drama of Hideo Kojima proportians, nor is it as puzzling as some Zelda dungeons. Instead, TMNT is most like a straight forward brawler. A few levels with missions and bosses at the end and little more. No multiplayer, no secret areas, but there are trophies to collect, and minigames to play courtesy of April, Jason, and Splinter.
Sound has got to be one of the best areas of the game. The music may be bland but there are sound effects for a lot in here, and it makes the 2D brawler seem to be teeming with life.
Gameplay is very simple with all the buttons getting used for walking, jumping, attacking and calling a turtle to help. For all intensive purposes, this could have been a re-make of the classic turtle games that used to populate arcades everywhere.
What it all comes down to is that TMNT is a very straight forward brawler, and little else but that's fine. Kids that have seen the movie will likely enjoy this the most, followed by fans of the older games.