I mean, I love Ender's Game (the book-- if that was unclear). I think it's fantastically written and has some important messages and social commentary. I'm also fairly certain it influenced Mass Effect, which is one of my favorite video game series. And even for those who haven't read the book, the movie probably seems pretty appealing-- powerful child soldiers, space wars, aliens. But: Orson Scott Card, the author of Ender's Game, is a gigantic homophobe.
I don't mean the subtle, garden variety "oh, you know, I'm fine with gays, just don't, like, hit on me" kind of homophobe, either. Nor is he the laughable kind, like the Westboro Baptist Church has become. He literally said that the legalization of same sex marriage "marks the end of democracy in America" among other really nasty, bigoted things. And he's part of the National Organization for Marriage. And he-- probably emptily-- threatened to go up against the government should same sex marriage be passed at a national level.
Which, you know, people are entitled to their own opinions and all, but he puts money into anti-LGBT organizations that make life harder for people who are already at a distinct societal disadvantage. And seeing Ender's Game in theaters would be giving him money, which, symbolically speaking, is giving him support and is, literally speaking, giving him the means to donate MORE money to bigoted organizations. Which is something that I definitely don't want, the LGBT community doesn't want, and is something I'm sure at least a few other people would like to avoid.
So what I propose is a boycott. If you want to see Ender's Game, I suggest doing so through means that won't give any profits to Orson Scott Card. I don't necessarily mean seeing it illegally, but I'm not saying that's out of the question either, depending on your morals. If you want to read Ender's Game, which I suggest over seeing the movie out of personal taste (the movie trailer didn't exactly leave me impressed, but that's just me), try borrowing it from a friend or through a library, or getting it at a secondhand bookstore.
And to be clear, I suggest this mainly because he donates money to anti-LGBT organizations. Everyone is entitled to their own opinion, but opinions don't exist in a vacuum-- opinions that can cause harm to others tend to do just that at some point, on some level. Orson Scott Card just happens to do this on a particularly big level.