Check out Hollywood Gothqiue's review of TMNT here.
The movie is sadly rather dull and unexciting. One thing that puzzles me is why Hollywood thinks action is really thrilling when rendered in computer-generated animation.
In a live-action movie, if you see Jackie Chan perform some outrageous stunt, half the thrill is knowing that he really did it (even if it took him a dozen takes to get it right for the camera). You're impressed with the ability to overcome physcial limitations and make something happen on screen that looks impossible.
None of that is in operation with CGI. You can have the characters literally do anything, but so what? It's not real; it doesn't look real; and more often than not there's no artistry or stylistic brilliance that compensates for the lack of realism. What you see is just a noisy, overdone videogame. Big deal.