Not her best effort, in my opinion. The book hints of many ideas, but full development of same is lacking. This seems to be a popular book among genre fans, but I suspect more out of respect for her abilities than actual content.
At first, I was very confused by this book. It starts with, really, a short story setting the far background for the whole series. I think I wouldn't have spent as much energy with the first part if it didn't talk about specific names of people, but talked about them as their jobs. The first part is really ignored once you get into the main part of the book; basically, it is a throw-away part, except that I assume it sets the stage for some events to come (there is some foreshadowing about tying that first part into the story later).
After a confusing and slow-moving first part, Cherryh is quite successful in getting you hooked into the different characters, and their interactions. As the human, Bren, tries to navigate the various political and relational landmines around him, you really come to empathize with him, and then root for him to tie it up.
Luckily, he doesn't tie up everything, just diffuses the situation with a LOT of help from his "friends" (I know, atevi don't have friends). I say "luckily," because then we can enjoy more books that follow!