Ender's Game is a classic YA fantasy novel about an incredibly intelligent (and basically grown-up) little boy who has been chosen as the person who can save mankind from the buggers, an alien race that mankind fought nearly a century ago. Ender isn't exactly aware of this and is forced to become a leader and overcome all sorts of miserable obstacles. He's a child that is and was never truly a child.
I read an interview with Card in which he describes his style as American Plain (or something along those lines) and that is a fabulous way to explain how he writes: plain and simple. I don't really enjoy that style and I think that's where my issue with the book lay: I generally remembered I was reading a book instead of being completely sucked into the story with more descriptions and emotions, etc. I love forgetting that I'm reading but Card didn't really achieve that for me with this work.
A few years ago, I did read another fantasy book by him, Enchantment, which I liked, so I'm not ruling him out by any means.