It's been a long time since I've read a book as good as The Golden Compass. It's got the feel of a children's book, largely because the protagonist is an eleven-year-old girl, but it's got some portions a bit too violent for young kids.
The book's setting is fascinating: Europe in the 1800's, but an alternate timeline. In this world every human being, without exception, has a type of familiar called a dæmon. It's like a pet, but it's there from birth, and it's magically tied to its human. There are also other pseudomagical, vaguely steampunk elements in the setting such as anbaric power, which is roughly analogous to electricity, and atomcrafting, which is a sort of primitive nuclear science.
The book's main character is a tomboyish girl named Lyra, who is raised at a university and ends up going on a grand adventure. She meets a hydrogen balloon operator from Texas, a group of water-nomads called Gyptians, a talking polar bear warrior, and a race of witches.
The book has been made into a movie, which should be released this December. If you're interested, you can view the trailer right here.
It's a shame that the book ends on a bigger cliffhanger than any TV show season finale I've ever seen, but it's a fantastic story, and I'll be picking up The Subtle Knife soon.