Not that I didn't enjoy it, but I have to say this was a bit disappointing for the most part. I think part of it is that the story would work better if it was set on a different world, because the way the big Dark King and the battles between good and evil are explained strike me as unbelievable if they are to fit in the history of our world. I know the characters say that "not all history is written and not all that's written has passed" or some such thing, but without some actual in text evidence it's just hard to swallow.
There are three main POV characters, and while I kind of liked Violet and by the end I actually liked Will, I still didn't love any of them and Katherine was just a walking book stock character (naive 19th century lady who liked dresses and frills and is mostly concerned with her reputation has been done before so many times, and this iteration has nothing new).
Now, while I liked the way the book ended and will want to read more, I really don't like this thing where the writer puts you in the head of a character but somehow manages to keep crucial information that the character knows hidden from the reader until some big reveal at the end. If that was the way it was to be, then I'd rather the narration keep off the characters' heads or the character in question not to have a POV.