A lot of tmnt adaptations I have watched always failed to showcase the 'teenage' part. They always seemed young, but never the 15/16 years of age they were meant to be.
This movie didn't do that - their characterisation was amazing! They really showed the innocence and laughability of the turtles - they were 15yr old boys if I'd ever seen one.
The animation is also fabulous, and really leaves you wanting more!
PSA: Stick around for the after credits scene, it's not a very long wait, and definitely worth it.