When I was younger, I used to be a pretty big fan of the Turtles cartoons, but I never found the attempts to bring the series to the big screen very successful. I didn't even know this feature-length CG animation existed until recently, so needless to say I didn't expect all that much going in.
I'm not really sure how this ties in with the rest of the franchise, the timeline and the characters felt a bit off to me, but in the end that wasn't the film's biggest problem. The weak villains, crummy art style and lack of atmosphere are way more damning problems that made it exceedingly difficult to draw any enjoyment from the film.
Shredder is dearly missed, the overly shiny, almost metallic-looking CG is a true eyesore and the soundtrack is just regrettable. At least the action scenes are somewhat fun and the film isn't too long, so it never really drags, but what could have been a fun update is just a dreary reminder that the best Turtles year are well behind us.