I'm glad I read the great Obscura burning first, as the first part of the book wasn't to my liking. It was too noir-detective story to my taste. When the second part began, I was totally drawn to the story - I really liked this part with the soldier life and the rebel camp.
After finding out who Cyrus really was, the ending was interesting as well, even if we came back to the same setting than in the beginning. I can see why the structure is like it is, but can't help to wonder if having only two parts would make it even more readable.