The Adrienne Rich poem at the beginning set my expectations for this book way too high.
I thought this was going to be a badass adventure story about a witch destroying patriarchy. Instead it's about some woman becoming a medieval knight's fuck-sleeve (more or less the actual terminology used THROUGHOUT THE BOOK.) The world of the book sounds interesting but is never developed. Likewise for the magical lore, or even the MC's character development. Instead, we spend over 300 pages as the main character does nothing, with a barrage of rapey sex scenes that could only be hot to the most repressed of heterosexual housewives.
I literally threw this book out the window at the end, when after waiting for so fucking long to see what happens when they go to war, the story ends on a cliffhanger. I will not be reading the sequel. This shit sucked.