I'm sure someone somewhere on Gawker wrote about this, but I couldn't find it. I finally saw the movie this week because it came to cable and I didn't have to pay extra to see it. These days, I refuse to put extra money into Orson Scott Card's pocket because of his activism against marriage equality and other reactionary positions. If I absolutely need to read one of his books, I will buy it used.
But back on topic. This movie was a disaster, both as a movie and as an adaptation of the book. It is always difficult to adapt books where the character's inner monologue drives much of the plot. Without understanding what goes on in Ender's head, the book is nothing at all. And an essential part of what goes on in Ender's head is the way he is worn down and demoralized over a period of years. This is not conveyed at all. Not at all. If they tried, they utterly failed - but I don't think they tried.
The repeated references to Peter? That's another complete failure. All we get is that he's a bully, not a sociopath. Maybe they were afraid that a scene eviscerating a squirrel would get them an "R" rating, and they wanted the child audience? I have no idea. But they turned an essential part of the book into a two-dimensional "I don't want to be evil like my brother" trope. Okay, you don't want to be evil like your brother. You keep saying it. We get it. We don't know why, but we get it.
The young actor playing Ender may be one of the worst child actors I've ever seen. He's completely wooden. Perhaps that is how he was directed to play the character, there's no way to know. It would not surprise me, since the rest of the direction was so tone-deaf. He may be a fine young actor, but it did not come across in this film.
The absolute worst part of the movie was the final sequence, where Ender and his team are on the Bugger outpost practicing maneuvers. As anyone who has read the book knows, this is a long sequence where Ender and the others are pushed beyond mortal limits. Several of his team have breakdowns. Ender is having nightmares and engaging in self-harm in his sleep.
The final atrocity is the way they changed the final battle. Ender did not destroy the planet to ace his final exam. He destroyed the planet in defiance of the gamerunners, of Graff, of Mazer Rackham, of the whole system. It was a giant "fuck you, I'm not doing this anymore, I'm not playing by your rules anymore." Changing it to an act to please them is a complete betrayal of the climax of the book. I wanted to punch the screen and turn the TV off right there. I don't know what story they were telling, but it wasn't Ender's Game.
I may not like the author of this book, but it is definitely one of the best books I have ever read. Yes, it is a bit dated post-cold war, and the technology could be fresher, but that's true of a lot of classic SF. It's still brilliant. But it is ultimately the story of a highly sensitive and intelligent child being molded into a weapon, and almost all of what made the book brilliant was lost in the movie. Some books aren't meant to be movies. Perhaps this is one, I'm not sure. I would have said Lord of the Rings was one, but I was clearly wrong. The fact that this takes place over a period of years does make it more difficult to adapt, but other movies have managed to deal with that problem. This adaptation did not.
All in all, I recommend you skip this movie, especially if you loved the book.