The book: The fourth in the series; if you have not read the others, I suggest you start with Sharing Knife: Beguilement!
Having finally arrived at the mouth of the Grey River, Fawn and Dag decide to visit, and maybe stay at, a nearby Lakewalker camp, so Dag can work on his big plans to help farmers. Lakewalkers opinions on this are divided, of course... Whether Fawn can find fulfillment in playing a minority wife, or if Dag can change old Lakewalker traditions; or if they have to take off again - read the book.
The writer: Lois McMaster Bujold has written both s.f. and fantasy; the Sharing Knife series is a fantasy overlay on early Mississippi travel/adventure.
My opinion: better than part three, I think, even if the book comes over as leisurely, rather internalized, in places... Not the best book to *start* reading Bujold with (for that, try an early Vorkosigan, or the Curse of Chalion); but still essential fare in this series, as it is the final volume, I think. It could go on, there are enough story threads to embroider on; but it feels like a satisfying conclusion, too. It is moderately easy going until, say, page 300, when Bujold lets rip with exciting action scenes again. But with a storyteller as good as Bujold you don't need speed to make it all interesting. She is very good at drawing you into the people, the relationships, the developments, and keep it interesting 9or even fascinating) on relaxed passages.