"The Golden Compass" is the only book I ever bought on the basis of its cover illustration. The picture of Lyra, Pantalaimon and Iorek on the front was very cool.
I read it and loved it. I loved the combination of fantasy and sci-fi elements, and the story was intriguing, and the end was a great cliffhanger. I loved it so much that I went out and bought the sequel "the Subtle Knife" the same week as I finished "Compass."
I was disappointed. It's not that "Knife" was bad, but it was definitely a step down from "Compass." There were lots of cool ideas in it, but the whole thing seemed less coherent. "Compass" was tightly focussed and suspenseful, while "Knife" kind of meandered. I wasn't sure why people were doing a lot of things or where the story was supposed to be going. Then half of the characters suddenly die three-fourths of the way through, and some of the other characters get special powers for reasons that aren't really explained.
So when "The Amber Spyglass" came around, I didn't buy it, but I was still curious to see how the story would resolve. This time I was
very disappointed. Coherency? Pshaw! The whole story is a bunch of random events that are barely explained and not logically connected. The previously established rules of inter-dimensional travel are tossed out the window. Villains are suddenly heros and new villains spontaneously appear from nowhere. People are endowed with cosmic powers for no apparent reason. The end comes as a dues ex machina. Loose ends dangle left and right.
In sum, the trilogy was possibly the biggest literary letdown I've ever experienced.
As far as I can understand, the only reason these books are popular is because they were reviewed well and pushed in the literary media: I don't think they would have remained popular by their own virtues. And the primary reason they were praised by reviewers is because they are explicitly anti-Christian and therefore cool and trendy. Never mind that the quality of literature declines precipitously as the series progresses, it's got the correct values, and that makes it good.
If I were you, Amory, I'd quit while I was ahead. Stop with Compass, because Compass is really good. Reading the rest of the series will just spoil it.
Incidentally, this dovetails with something I'd wanted to say about "Speaker for the Dead." I really liked Speaker. It sits proudly on my book shelf at home (next to The Golden Compass, as it happens). But, like Compass, it ends on a cliffhanger, and the books that follow do such a terrible job of resolving it that you wish the author had just left you with the cliffhanger and not tried to write an ending. "Ender" was great. "Speaker" was almost as good. But "Xenocide" and "Children of the Mind" both sucked real bad. Read "Speaker," but skip the sequels. You're better off making up your own ending than watching the author's initially strong ideas fizzle out and die.