This is the least compelling of the Kushiel Universe novels, and that seems to be a general consensus. In fact, if I weren't such a die-hard Carey fan, this novel would have found itself on the 'Did Not Finish' list. I'm only giving it two stars, and even that's just because Carey is a good writer.
I think part of the problem for me is that Moirin spends most of this book under the thumb of a religious zealot, forced to confess her “sins” and turn everything she loved into something horrible. I guess it's a testament to Carey's writing prowess that this hurt me so much, but I think I took it just as badly as Moirin. It sucks. It's not fun at all. I read to escape those kinds of things, not revel in them.
That's not the only problem, though. The book is just lackluster. It's an obvious contract-fulfiller, and everyone Moirin encounters seems to be very stereotyped. It's preachy. It's just...meh. And I've read it more than once now, and I still really disliked almost all of it. I probably won't read it again even on subsequent Kushiel read-throughs. It makes me sad, and that makes me even more sad compared to the amazingness of the rest of the Kushiel books. It could have been so much more.