I finished reading a moment ago and I enjoyed it a lot. What I liked was that not anyone was presented as infallible and perfect. Even the Federation, which usually is "superior" in everything compared to the others, has its darker moments: keeping a former Obsidian Order agent as their ambassador (hehehe), or having not so skilled spy on Ab Tzenketh. I'm also glad to see Ferengi treated seriously and not as a comic relief as they so often are presented.
I'm not so surprised by Nata's choice, though. A strictly hierarchical Tzenkethi society had to be appealing to a Cardassian with strong hierarchical instincts. In spite of all disadvantages, Nata found the thought of staying there comforting and I can see why. I also found it touching how she cared about Cory.
I don't read all new Trek books anymore, but Ms. McCormack's books will always be on my "to read" list