Many years ago Orson Scott Card, the author of Ender's Game, said the book was "unfilmable".
Of course that was before Computer Generated Imagery, CGI, got really good. The movie Ender's Game still has a problem but the computer cinematography is not it. The movie is two hours long but another 30 minutes would have helped a lot. Maybe an hour could have made it as good as it could possibly be.
But having read the book multiple times I find the movie somewhat disappointing, but that is what I expected. Too much happens in the book, and too much that is inside Ender's head to come across well in a two hour movie. It is the psychological aspect for which Card said it was "unfilmable".
The story of Peter and Valentine, Ender's brother and sister, on Earth after Ender goes to Battle School is completely missing from the movie. But that is a factor which affected the ending of the story so the end of the movie had to be modified.
Maybe people who have not read the book can rate the movie higher but I can only give it a +3.5.
Movies have too much of a time constraint and maybe they need too large an audience to make money so the producers have to compromise and can't do what would appeal to readers since they are not a large enough part of the market.