This book definitely seemed like the second in a series. It tells the story from many different points of view (sometimes a little disorienting, but necessary, I think), and focuses more on moving the plot towards the third book than on character development. Not a "bad" thing, just the function of this book. I don't think it would stand alone without the other two. I enjoyed reading it and am looking forward to the third, but I wasn't as blown away as I was with the first. 
 Unlike other reviewers, I didn't find the religion talk heavy-handed at all. I still don't see how it's pushing an atheist agenda...if someone's trying to kill God, they certainly believe in God and thus can't be atheist, right? I'd like to see the alternate worlds in which Religion isn't confused with God, as it is in those Pullman has shown us so far (these worlds must certainly exist, if all possible outcomes exist simultaneously). I'll see what the third book has in store. 
 As a side note, I recommend reading this series at the same time as The Tibetan Book of Living and Dying. I didn't plan this juxaposition, but I think it's really put an interesting edge on my reading of the series.