This doesn't feel like a TMNT movie. Rogen's turtles feel more like teenagers, sure, but that's the extent of the improvements, if you can call it that. I wanted to like it, but he has thrown away the things that make the TMNT franchise entertaining and threw away origin stories for at least eight characters.
SPOILERS PAST THIS POINT!
Splinter got to be a cool guy for one scene, but doesn't show the kind wisdom and world knowledge that he's known for in every previous iteration. Instead we get a bigoted Father figure that even in realizing he's wrong, admits he won't change his ways. Those eight characters I mentioned? Eight of the featured mutants. They all came from the same experiment, grown in test tubes. Bebop and Rocksteady are diminished to background characters with no personality. Bebop was born a pig mutant with no history with the turtles, yet still has his turtle shell pauldrons. A half dozen or so other mutants are shoehorned in for no other reason than Rogen played with the toys as a kid. Mondo Gecko was given more personality than anyone outside the turtles and April. Mondo is great, but the rest of the "villains" are basically just present in the movie. The ending with the turtles just going to regular school was dumb. It might be the worst part of it. They're meant to be humble heroes fighting largely from the shadows with some exceptions and doing so in spite of the fact the world wouldn't accept them as "normal people". They use disguises to walk around in public, and acknowledge that most humans would fear or hate them. They continue to help humans because they know they are in a unique position to do so. They're supposed to be taught by Splinter that it's the right thing to do. We got a taste of that in this movie, but it didn't come from Splinter. It's a throw away line by Leo and they're immediately accepted by the people of New York. The only reason I'm not giving one star is because the fight scenes are pretty fun.