This trilogy is mostly about Jinian, who becomes lover/wife to Peter, the protagonist of the first trilogy. Her story skips most of the part where she's in his books, although she corrects some things he remembers wrong.
It's an interesting story, tied into the earlier six books, but with a different aspect of life in that time. Jinian learns a lot from many people, including the original intelligent beings on the planet, and at the end learns something that enables her to defeat the immediate evil. There's a mostly happy ending, but the moral of what she learns is pushed a bit. I still think the fifth book of the nine is the best, but it can't be read without the others.
This is nominally SF, but there's no doubt that the SF is trappings and it's really fantasy.