The movie suffers from the compression of the novel -- the audience deserved more of the battle room, if nothing else, and a better idea of how grueling the schedule there and in Command School really was -- it looks like a couple days at most.
But the biggest issue with compression is moving command school to near the Formic homeworld. I couldn't figure out why, especially as they kept with the concept of instantaneous control with the ansible (FTL communication). But it was mainly so that they didn't have to break from Ender's shame at his destruction of his enemy to the hope of restoration by finding the last queen's egg.
Ok, I can see how that helps streamline things, until you realize that, uh, he just stepped off a military base, brought something alien back with him, and now he's going to traipse across the galaxy to find a place to put it? Um, no. That can't happen until he's already been out of the military.
They should have split it in two: Battle school, maybe up until the first victory of Dragon Army (going any further leaves too little for a second movie), then the rest. That would have let the characters breathe, let them have a decent epilogue reuniting Ender and Valentine, and the Hive Queen, and maybe even some way of bringing in Locke and Demosthenes.