>I guess the main problem is trying to translate what works on literature to cinema. As those are radically different languages, the focus should be on different things.
>

That is one of the big problems. About 10 years ago I talked to Orson Scott Card about doing an Ender's Game movie. He told me it wasn't going to happen because it would be impossible to do it. At that time, it was due to technology limitations. Those have now been removed and a movie is in the works. http://www.frescopictures.com/movies/ender/endersgame_update.html

Because Scott is heavily involved with its production, and knowing Scott's desire for keeping the story intact, I expect this movie to be really good.