Other reviews here have gone into detail with some enthusiasm about the plot (or lack thereof), so I won't address it here. The author has some worthwhile insights into her society and, to her credit, has developed a supernatural culture that is of some interest. The culture appears to be based solely on the sensual, primarily sex. Like an x-rated movie, the entire purpose of the book appears to be to set up situations where the "heroine" can have sex with her many partners, and in my opinion, that makes this book porn. Soft-core porn, but porn nonetheless.
Ms. Hamilton explores her supernatural from an insider's view, and the point of view can allow for some interesting situations. Her characters are distinct, though you can't help feeling that the purpose of the book is to work out the author's own sexual fantasies with the main character as her avatar. I found the author's prose pedantic, and thought that it only lifts above the coarse when the author addresses her favorite topic, intercourse.