His Dark Materials... ooh, yes!
Like you, I got hooked right away. I think it was the setting most of all. Alternative reality with dæmons, clockwork and just a little touch of steampunk. But just as much the Lyra character. Strong and flawed, that's how it should be
Philip Pullman strikes me as a man who knows
precisely what he's doing. He understands the formula, and uses it excellently. He writes Young Adult fiction that truly respects the reader, challenging their intelligence and norms. He's quite on par with
Astrid Lindgren, which is probably why he won the recently founded Astrid Lindgren Memorial Award.
Northern Lights/The Golden Compass seems to me to be the ideal YA Fantasy, even though it alone presents themes more mature than a lot of adult fantasy. The maturity progresses through book 2 and 3, although it may be a bit much of the good thing.
I've also read
Count Karlstein, which goes more along the lines of Magical Realism, and is nearly as excellent.