The Turtles personalities were nailed...
I've seen a few people say this and I don't understand it. Yes, they each portray that singular character trait they all have (Donatello does machines, etc.) - except for Leo, who doesn't seem to lead or do much of anything. However, we see barely anything of their relationships with one another. They try to force the family thing in at the end, but we hardly ever seem them interact or relate. I feel like they each had about 10-20 lines each in this 2 hour movie, and by the end they were all still total strangers aside from what you know of them from the '80s cartoon theme song.
What I am shocked about is how the executive people at Nickelodeon would even trust these people to create a good movie.
The deal for this movie was signed before Nickelodeon bought TMNT. I'm sure they weren't ecstatic about the quality, but it has already made more than they paid for the franchise anyway, so I'm sure they don't mind.
Also, it was painfully clear that the script was re-written mid-shooting so that William Fichtner wasn't the Shredder and was just an apprentice. Dude's name is even Eric Sachs (americanization of Oroku Saki), and Shredder is barely even a thing in this movie aside from some giant monster that shows up when Fichtner conveniently disappears.