Maybe because there were so many key characters, it took me a good 100 pages to get into the book. But once it started going I was incredibly engaged. I had no idea who the final antagonist was, but loved when everything was revealed.
The book was great, though too much ‘romantic interest' for the first 3/4. Then the romantic interest resolves into some more graphic sex, and the two main characters can't seem to function without thinking about live and relationship. It generally ruined the book for me.