I thought it was a decent movie in the TMNT franchise. I'd rank it third best out of the first four movies in the franchise. TMNT III is still the worst, a significant step below this computer animated film. I'm a big comic book geek so I typically enjoy comic book themed movies. My kids enjoyed it too and we are now set to watch the first of the re-booted TMNT movies, released in 2014. Can't wait!
Side note: My favorite TMNT scene in any of the movies is the Vanilla Ice cameo in the second movie. Go Ninja Go Ninja Go! :-)