Just finished it, and it only took me a day so it is either great or good by my scale.
Ms. McCormack, like in Hollow Men, takes two stories that seem to be seperate, then unites them in the end giving you that "ohhh, that's what was going on" feeling.
Picard doesn't seem to be doing much in this book. Ezri just seems to be there to cast suspicion on Peter and to have the Aventine be there to recover Efheny. Poor Crusher gets shafted for the greater good. Beverly tries to put her ideals into practice but soon finds out that she is on the bottom rungs of the totem pole and the rungs up top don't have time for her nonsense. The Federation is in a "with friends like these..." situation in that the Ferengi will cut a deal on their own if it suits them and the Cardassians have their own plans.
Did Efheny go a bit mad? I still don't quite get why she stayed. Did Alex go a bit mad as well? It seems that spies aren't doing a good enough job blending into Tzenkethi society and it's only the belief by the locals that they're lower caste trying to be upper caste, is what keeps them from being caught all the time.
Picard should change the expression from "anyone remember when we were explorers?" to "anyone remember when we had principles and ideals?" I know they have mortal enemies surrounding them and all but, it's gettin pretty grim.
I liked the fleshing out of the Tzenkethi and the Venette were an interesting addition to the Trek races. The OCD in me was looking at Geoffrey Mandel's Star Charts to see how you can border the Cardassians and the Ferengi at the same time.
The Lotus Flower was my favorite story in World's of DS9. The Neverending Sacrifice was great but Hollow Men was average. I'll give Brinkmanship an above average.
I felt that she wrote Picard a little too grumpy right from the beginning of the novel. Don't get me wrong...she wrote Picard effectively and she made it easy to see how he can (and probably will) become an ambassador someday. But I got that "grumpy Picard" vibe right from the very beginning.
Efheny stayed because ab-Tzenketh is such a remarkable world in every single way, especially compared to Cardassia. There's practically unlimited resources there.