Years ago, we bought "Northern Lights" (Golden Compass in America) for our son. It lay unread in a corner of his room for months until I found it. Having nothing else to read at the time (I'd re-read x times the books I had!) I looked into it.
I was stunned that this book was aimed at teens, when you look at the deeper message - and once I finished it I HAD to get the last two!
Pullman has put a huge amount of thought into this trilogy, along with, dare I say it, spirituality. His semi-atheistic view of the land of the dead, and the aftermath when the dead are finally "freed" is quite thought provoking.
I bought "Lyra's Oxford", but it wasn't up the standard of HDM, it seemed more like a souvenir, a book sized badge for your bookshelves.