First off, this very-well-written, well-researched book is not focused on erotica, though it has aspects of harems, slavery, bondage, and incidentals about SM that happen to "others" in the story.
This is, foremost, a story of one woman's overcoming her forced slavery - in both her mind and eventual physical escape. In that regard, it's a gripping tale of rising above the most difficult of situations, the ability of the human spirit to survive, or not, and the triumph of love in some cases.
The story has a talented touch of realism and the author draws you in and makes the tale compelling.
If you want to read an erotic story for the turn-on, this tale offers something to readers who are into bondage and cruelty, but nothing directly to those who are into light/heavy body modification, fetishes (except really bizarre stuff that's kind of yucky), hair, etc.
That said, this is a book worth reading for its literacy and its story quality.