Allowing for the fact that I never read the book and I never was a boy–what the fuck was that hot mess? Let’s just start with the fact that, on a planet with seven billion people, why did they keep being all “The aliens killed tens of millions of people.” We have seven billion people on a huge planet. And I’m supposed to believe that the whole world came together because an intergalactic force wiped out Southern California? We couldn’t all come together to stop Stalin and at the scale of space, he lived in the same house with us, sat on the same couch, put the moves on whoever had the middle cushion, even if we were dating them. Couldn’t the aliens have killed a billion people?
But the main problem with the movie, frankly, is that it tried to hew too close to the book. Ender’s family could have been way parred down because all that shit about being a third matters in the book (I assume) but means nothing in the movie. We needed less time with the whole “Ender beats up bullies” and more time with “Ender is having something weird with this game.”
But the Butcher and the Red-Headed Kid looooved it. Loved. So, you know, to each their own.
Tiny Cat Pants 
The novel itself was bloated. The novella it was based on was much better, though it sure did display Card’s template for undeservedly suffering, misunderstood heroes that have been his stock in trade ever after. In fact, thinking about why I came to dislike his books, I realize that the perfect fit of actor and source material would be to have Mel Gibson star in every movie based on any of Card’s books.
I have to admit that I kind of love the idea of the egg from the end of the movie and Ender growing up to be Mel Gibson and… well, anyone, really… and doing some kind of buddy cop movie set in outer space.