I think the movie adapted the book better than they did with the Harry Potter books. Or most everything else.
As someone who tries to watch the movies first, so I'm not let down, I was a bit afraid going into Ender Game because I found that book series very early in life. I would have wanted the movie to be longer, but I respect how well it followed the source material while making a very slow and methodical book accessible to a general audience. Even going so far as to include the lake scene and the egg scene.
It was much better than the critics at the time would admit. Many of them are critical of the movie just because they hate Orsen Scott Card.