First read it about ten years ago, some months after having bought it for 20c as old stock from the library. Picked it up to read in bed for a bit before sleep, not really expecting much. Finished it at about 3am. Read the whole thing again later that day. The most surprisingly engrossing book I've read.
There are sequels as well, which I didn't read until quite recently. They're very different books, showing Ender later in life. The first one, 'Speaker for the Dead', is an even better book than Ender's Game, and I don't say that lightly. But it is very different. While Ender's Game can appeal strongly to teens and adults both, the later books are more adult oriented. Then again younger people who read this sort of science fiction tend to be a bit precocious anyway, so who knows .
