At the suggestion of a friend I picked up The Ender Quartet Box Set: Ender's Game, Speaker for the Dead, Xenocide, Children of the Mind and set about reading through it. I'm currently through the first two books, Ender's Game and Speaker for the Dead. Overall, I liked the first book, scary though it was in terms of potential parallels with the future. It just didn't seem far-fetched enough, I guess (just like Orwell's 1984).
In contrast, the second book (Speaker for the Dead) was interesting, though it was a more challenging read. I think I enjoyed the story, though it was kind of, um, different. I don't know, maybe I had just become too jaded after the first book. The biggest thing that jumped out to me was the disconnect between timeline and technological evolution. The book jumps forward about 3,000 years, but the tech seems not to have changed all that much? That seemed rather odd to me. *shrug*
Overall, I think the series is interesting and worthwhile, though I'm taking a break (reading more of Pratchett's Discworld series) before I finish off the quartet.