Spoilers sweeties!
Pretty much agree. The first book is the best. Having a whole bit in the 3rd book about a species simply to challenge the idea of Intelligent Design, and the death god was like being hit over the head with a wholly unsubtle stick rather than knife.
I liked the design of the TV series but got bored by it.
Agree about the books, especially about the third and the death of God, which seemed pretty limp-wristed to me. Even Pullman's bugbear C.S. Lewis could do better than that (on occasion, and of course with Lewis it was the other way round)
Pullman has a marvelous imagination, but at times it seems to fail him.
The TV series has some fine special effects, but some of the subtlety of the Subtle Knife is lost all round.