Just watched for the first time on Netflix.
I grew up with the Turtles and I heard this movie was either terrible or pretty average from most people. I went in without any expectations, and I actually didn't mind it. It wasn't great, but I felt like it was way more watchable than, say, the Transformers movies. I had a few chuckles here and there and, for once in my life, thought Megan Fox did okay in a role (there were better choices, but she's clearly a little better at acting now than she was several years ago).
My only two BIG gripes with the movie?
1. I think that they tried way too hard with Shredder. They wanted to add too much detail to him that he just ended up looking like a cluttered mess. Kind of the same problem that Bay's Transformers suffer from as well. They just went overboard with his design, and I think that they should've kept it simple.
2. Way too much focus on Raphael. It seemed like the had the most chances to shine in the movie, and his backstory amd personality were pretty developed while Donatello and Leonardo weren't even really touched. If it wasn't for Michaelangelo's silly personality coming through well enough in the movie, he'd be in the same boat as the other two. Overall, there was just too much of Raphael taking the spotlight.