Part of what helped the books' predecessors to succeed was the balance of history and fantasy, that provided much fuel for plot movement. This is the most supernatural of the series, and unfortunately the plot has been compromised. Pretty much the only thing propelling the first half of the novel is Annith's desire to break out of the convent and get some answers. So we get a lot of vignettes and little scenes of her on the road that help to pass the time, but they don't amount to much in the end.
It's only when Annith finally reunites with more familiar characters that she intersects with the main world of the series, and only to tie up loose ends at a point when most of the action has been completed already by Ismae and Sybella. Even then, the ends in question are tied up in an increasingly ridiculous manner. At one point, a certain deity in the flesh stands around in a war-room with a bunch of advisors, pokes at a map and says, "That is a lot of occupied ground to cover with no escort."
Yeah, sorry, nope. An ancient and inscrutable god, the stuff of myths and legends and theology, and that's what he has to offer? Really? LEAVE MY GODS SOME DIGNITY.
Where the plot falters and the supernatural fizzles, the romance fails to compensate. The male lead is appropriately swoon-y but in an overdone sort of way, and the relationship between them is not as convincingly and deeply built as we've seen before. I still read the novel from page to page as it falls into a genre I enjoy; and it did tie up the trilogy quite neatly, in a way that suggests the author started on this series with an end-game in sight, but that's the only reason why this gets 2 stars. Disappointing; she could have done much better.