Orson Scott Card published the book Ender's Game in 1985. To get things in historical perspective, this was the year that Windows 1.0 was released. It looked, according to Wikipedia, like this.
It would be easy to assume that large sections of the film were 2013 glosses of the 1985 book - but the fact is, Card's view of the future as portrayed in his books was close enough to where we are thirty years later that it is basically recognisable - if you read the book today, there's nothing terribly anachronistic about the world it portrays, and there's much SF that hasn't aged as well as that.
Other reasons that I was impressed by the book were:
- Rather than a bland philosophical naturalist, or artificially pantheistic world in which everyone lacks any sort of cultural identity, in Card's world, people have national and religious identities, within the context of what seems to be something like a world government. This is reflected in the film.
- Children are portrayed as morally complex. Probably a bit too morally complex - the idea of Ender being a small child (i.e. about 6!) doesn't make it into the film - I guess he's supposed to be closer to 12. And the language and imagery that shapes the children in the book is omitted as well - the alien race, the "buggers" become "formics", for example. But the book portrays a childhood world that is much closer to reality than what tends to be presented by children to adults. This in itself makes Ender's Game an interesting subject for children's literature.
- Some of the ideas in the book are really life shaping. Look up Demosthenes' "hierarchy of foreignness." Again, think of how xenophobic and insular the world was in 1985 - Europe was still divided by the Iron Curtain. In this context, Card was making the case that, if other people shared our humanity, or even if inhuman but communication was possible (!), then there ought to be an alternative to war and destruction.
So, what of the film? Technically, very good. It was a real shame that the complex political and social aspects of the relationship between Valentine and Peter aren't developed - but you have to sacrifice lots when you go from your average book to your average film. And I'm sure the people who read the book as children or teens would love to have seen more games in the battle room. However, what was brought out much more strongly in the film was the climax - not the final battle, but what happens after. I'm trying to avoid spoilers here - but suffice it to say that Card's message about the need for tolerance and almost pacifism, is made clearer in the film than it was in the book.