I just finished this book in geometry class, and let me tell you, it is fantastic! It has everything you'd ever want in a fantasy epic - love, treachery, amazing imagry, well-developed and likeable characters... Pullman really pulls you into the series, especially this one, with the blooming romance of Will and Lyra(who despite their age are obviously quite mature, although some people who read this might feel a bit confused at their ascent).
The only thing that really bothered me was a chapter, no, not even a chapter, a fragment of a chapter, in the end when Pullman uses one of his characters to vent on his atheism. I'm an agnostic, so either way, it doesn't so much matter that he's bashing orthodox religion... The fact is, it doesn't make sense that people could go through so something so eye-opening and fantastical and then openly outrule the existence of something like a creator. It was obvious that he was absent, but non-existant? Isn't that just as rediculous as orthodox religion? Pullman needs to read his own novel, I think. Anything's possible. That's the message I got, anyway.
Either way, the book's a great read, and the best in the series. Read it; you'll enjoy it.