This is a wonderfully complex conclusion to what I refer to as the Clockwork Earth series. What I liked most about this novel is how the major changes occuring in the clockwork setting are mirrored in minds of Paulina and Boaz. What is depicted is the coming together of faith and reason and also the incorperation of free- will into a previously deterministic reality. And also, there is a wonderful metaphor of the "Golden Bridge," being like the connection between the right and left hemisphere of the brain; with the right being the Southern Earth and the left being the Northern Earth. There is also a strong suggestion of pantheism with the Mind of God being divided between the Silent World of the Southern Earth and the Judeo-Christion God of the Northern Earth.
I especially liked Boaz, who reminds me of Star-trek's Data. I was fascinated by this clockwork automaton's mental transformation from machine to human, which closely reflects the Clock-work Earth's transformation to a more free-willed and blended state. This, in my mind, makes this series similar in theme to the Veil trilogy by Christopher Golden. In that series, there is also a few characters whose transformations parallel the transformation of the setting; and the coming together of magic and reason.
The book's characters and setting was so good that I was disappionted when it was over.