So, while I don't plan to give away any major plot twists, I'm reviewing the second in a series, so spoilers, of course, if you haven't read the first, and probably light spoilers here anyway.
I'll note that my copy of this arrived while I was 18 chapters into the first Game of Thrones book. NIGHT AND DAY. Carey's prose is so much richer, her characters so much more complex, her paragraphs so much more unified-in-a-single-thought (okay, that last is just uncharitable; sorry to Martin). Sincerely, though, it was a breath of fresh air to pick this up.
I'll continue the Martin comparison a moment longer: Kushiel's Chosen is character driven and has a single protagonist; part of her agony and the reader's is not knowing what's going on with the other characters, and it's well-done. Unexpected things happen, but surprise is not the engine that moves the plot. There's a mystery, and there are good clues to its solution along the way, but Phedré is not Sherlock Holmes, and the ways in which she pursues her investigation are wonderfully consonant with her character as established in the first book and the early portions of this one. If she notices something, she notices it as Delauney's protégé and Kushiel's Chosen. If she misses something, she does it in the same way. If she makes a promise or breaks one, commits to someone or holds them at distance, suffers or rejoices, she does it as herself. And when she grows, she does it as herself, taking the experiences she gathers in this novel in, again, as Delauney's protégé and Kushiel's Chosen. Five star rating just for pulling that off with such a flourish.
The religious commitments in this novel are deeper than the first. The characters' traits are also more compelling to them, but without being at all charicaturish. Phedré continues to be a great heroine -- not talented at everything, but with a narrative voice that is incredibly mature and aware of her own strengths, weaknesses, successes and failings. It's fun to watch her grow. It's also fun to watch the other major characters grow: somehow this is accomplished in the background with elegance and grace -- no clunky exposition to catch you up to "Oh, now this person knows about her feelings and this one has killed someone in cold blood so he's a warrior now too."
I will say briefly that the fight Phedré and Joscelin have, and the playing out of its consequences, is SO much more satisfying than the idiocy between Bella and Edward in the second Twilight book, and a pretty clear illustration of what ACTUAL fantasy/romance can deliver (and we're talking the fantasy genre where there is a romance here, not checkout-aisle texts). Sadly, the sex and exploration of sensitive religious topics keep this pretty firmly beyond most young adult readers.
I heartily recommend the book to lovers of fantasy, epic, Tolkien, space opera (it's a different genre, but you'll find some familiar elements), and historical fiction. There's just enough magic, the religious landscape is incredibly well-developed, and the pacing's a lot of fun. I certainly intend to finish the series.
One note about that religious landscape -- Christ is known to have been the Messiah in this fantasy world's history, but there's also magic, other gods whose existence is left ambivalent but pretty-heartily endorsed, and the main character's national religious heritage is descended (as are the citizens of that nation) from angels who rebelled against God's disowning of a second son begotten accidentally of earth through the wounds of the Messiah. Carey doesn't fling this in your face, but if it's going to make you queasy, you're forewarned.