When I was a kid, I had pretty typical taste in Science Fiction. It was Heinlein, Asimov, and even some Piers Anthony.
This book changed how I thought about science fiction. It says something, not only about the fictional world, but about our world. Instead of being about rough sketches of a characters to advance an idea, it's about a child growing up and finding out what his world is and what it means.
At the same time... man, is it bleak. I recommend this book to everyone, but some people just put it down midway because they don't like the ideas that that world has to live by. It's not a book for kids, but that's why I loved it, and think it's a book that everyone should read.