Megan Fox & some other people at Comic Con

Megan discusses April's character & how her ass kicking scene ended up on the cutting room floor:

It’s all very….goofy. Don’t go in to ‘Teenage Mutant Ninja Turtles’ and expect ‘Batman Begins.’ This really is a kids movie and, from what we were shown, it’s playing that up. The adults in the audience might not laugh at the Keyboard Cat jokes but we’re not sure they were ever meant to.
We’ve give the look of the Turtles a lot of grief (and rightfully so based on some of the earlier materials), but that’s not even one of the film’s problems. In the context of the film, the turtles look fine. The mo-cap is done really well and while they don’t look like the classic Turtles of old, they’re not what’s holding the film back. One thing that really did take us out of the moment was the voice of Johnny Knoxville, who, with his Tennessee drawl, just doesn’t have the right sound for Leonardo – the no-nonsense leader of the team.
In the end, this movie seems like it’s Teenage Mutant Ninja Turtles by way of the new ‘Amazing Spider-Man’ movies. Light and fun and goofy, but with very familiar action beats and cartoonish heroes.

There is also an in-depth description of the scenes they showed at source #3