I think I need to call this one quits, as I've put it down several times and haven't come back to it for weeks now despite my repeated intentions to finish it.
I will say this: the world the author crafted was quite compelling. I wanted to know more. The characters are on the interesting side as well, though I think there were some serious issues with how the development of their relationship was handled (as in, not at all: one second they were strangers, the next second the big strong royal automatically and for no apparent reason cared fiercely for the poor little slave who needed protecting). Still, I really would like to know how the book ends.
Unfortunately, the writing is just painful. As other reviewers have mentioned, huge blocks of background text before each (too-short) chapter really break up the flow and pace of the book. I'm assuming they're excerpts from a history book or sacred text within the world, but really they're just info dumps that could have been hugely interesting if the writer had worked them organically into the story and instead just ended up boring (and sometimes confusing) enough to skim past. Descriptions--of the setting, and more egregiously of the characters--were long, overused, and unendingly repetitive. Conversely, in scenes with many people in a room, pronouns and details were flubbed such that it became quite difficult to figure out who was where and who was speaking. It was work to make my way through all the pages and pages of things I didn't need to know about to get to what I really wanted to see, which was how the story--a potentially quite excellent story, by the way--was progressing.
I want to stress how much I really wanted to love this book. The world was fantastically imaginative. The characters were interesting. The mythology the author created was clever and sucked me right in. But the technical aspects of the writing craft--how to construct a sentence, construct a scene, avoid info dumps, mete out description--were just too lacking for this editor's eye. If that sort of thing doesn't bother you much, then I would actually recommend this book for its sheer ingenuity. If reading the phrase "silver-blue strands" (of hair) fifty times in a hundred pages will make you want to hurl your Kindle against the wall, then it's probably best to avoid this one :)