In case the byline makes you wonder, I will pass on the explanation from the foreword. Ms. Ross is one of the people who wrote officially sanctioned stories in the Darkover universe that were published in the various anthologies that MZB edited, and MZB particularly approved of her writing, so much so that at the end of her life, MZB told Ross the general plot line of a series of novels and told her to write them, and so she did. This is the third of those novels, collectively the Clingfire trilogy.
If you haven't read the first two books in the trilogy -- one of them is The Fall of Neskaya, the other one escapes me, and the books are at my mom's and I'm back home so I can't check -- you probably shouldn't start with this one, because it is probably useful to know the continuing characters. But if you read this book alone, I think it would mostly make sense.
I read the original Darkover books, except for the last few written since then, 20+ years ago, and I was very fond of the universe then, but I haven't had my impressions refreshed very much since then. Ross' writing does seem like it's in Darkover, but it's a little bit off. Some of the things that happen in the book -- fiddling with the mythology (at least, I don't have any memory of Naotalba, the bride of Zandru and an obvious adaptation of Persephone), a peculiar laran power that is the basis of a lot of the story -- seem strange to me, and I don't know if they were Ross' inventions or if they were part of what MZB gave Ross as the starting point for the stories. For the first 100 or so pages of this volume, I was feeling a bit put off by this feeling of "this isn't quite right", but eventually I started getting interested in the story. The ultimate conclusion is already known to people who know Darkover (the novel takes place in the time of Varzil the Good and the creation of the Compact; we know that the Compact does come into force and the Hundred Kingdoms become the Seven Domains), but within that constraint, the fates of the individual characters are surprising. And Ross does manage to show us some interesting ideas about mind control powers and about how people who do evil things can still have enough good in them to feel bad about them. It wasn't a bad read, but it was less than fully satisfying.
A reasonably solid but not outstanding fantasy story. A must read for the true Darkover fanatic (at least if you accept the foreword's assertion that MZB laid out the plot even though she didn't write the actual words), but not for anyone else. 7 out of 10.