I’m with those who say you should forget the spoilers and read the book yourself, and you’ll be glad you did. It’s 400 pages but it’s a FAST read, you can easily finish it in a single weekend. However, I do feel compelled to expand on JohnT’s spoiler:
Ender attacks the bugger planet because he’s exhausted, disillusioned, and wants out of the game entirely. He thinks that committing a gross violation of military ethics (the general warned him NOT to attack the planet earlier) will force everyone to kick him out, and he won’t have to fight the “real” war. Of course, it turns out that that’s exactly what the brass was counting on him to do!
That’s just the main story, though. You’ll also miss out on stuff like The Giant’s Game, the rivalry between Ender & all the older captains, as well as
all the homoerotic subtext & excessive young male nudity which has convinced many readers that OSC’s pro-Mormon, anti-gay rants are just a front.
The Peter/Valentine subplot may be a little unrealistic, but it’s nonetheless intriguing since it predates internet trolling by a decade. Sometimes I wonder if their method has been used by trollers on the SDMB: “Hey JDT, get that Pit Thread started NOW!” “But I can’t! I’m in FAVOR of circumcision!”
As for the smarty-smart kids, you gotta remember we’re dealing with the top 0.001% of a future society which involves selective breeding and genetic engineering. It’s not that far-fetched, really. OSC once received a hate letter from a teacher who said she was around gifted children all the time, and they don’t talk like that…he wrote back to tell her, “Sure, they do. They just don’t talk that way around YOU!”