Read this one aloud to the boys. This time through, knowing the course of the story, a few things stood out. First of all, it's intense. Other authors create suspense, but Card creates intensity. The detail in strategy and mechanics of the game, and the demonstration of Ender's skills, it's all just as impressive on a second reading.
Also on a second reading, it's clear that Card is very good at not telegraphing certain spoilers. The spoiler of all spoilers occurs a good distance before you reach the end of the book so you are fooled (this won't be a problem in the movie, of course, because you don't know how much time you have left as you know how many pages you have left!). The seams where Card must have expanded this story from its original short-story form are very clear to me. I've only read the immediate follow-up book (also very good) but not any of the others in which he must really expand on some of the threads left hanging.
Card's ambivalence about violence in a story that, quite frankly, depends on it is a road for future analysis. The reason why you like Ender's Game is the strategy and the game-like nature of the conflict, the breathtaking intensity and intricacy of it all. In the end, Card makes you feel some shame for having liked it but doesn't do much more than that. That's deliberate but I need to read the later books to see where he takes it. Right now I can't tell if he's trying to have his cake (violence) and eat it too.
This was just on the borderline of being too intense for our nine-year-old, even with some judicious parental editing. Caveat emptor. But all the same, it must be one of the top 25 books of all time for me. Let's hope the movie can do it justice and expand it in subtle ways.
How high should I put the 3rd book and its follow-ups on my reading list, I wonder?