It isn't a perfect book . . .it is a vampire romance of sorts, which is a bit tired by now, and it does lapse into WAY too much exposition in some places, which makes me hear Brent Spiner's "Data" voice narrating. It moves pretty slow in the first half, although I tend to forgive that in a book where much of the early action takes place at a university library. And it is a character heavy book rather than a plot heavy one. This is the main complaint of a lot of Amazon reviewers.
Oh but some of the characters are wonderful! Several secondary characters are so well-written they really deserve their own books. And some of the ideas in this book are truly wonderful, too. And there is tea, yoga, books, cats, castles, knights, more tea, wine, conspiracies, alchemy, and AN OUBLIETTE in this book. Good heavens, what more could you ask for? AN OUBLIETTE!!!! So scary.
Also it has more tea in it than any book I have ever read. Did I mention that?
So if you like fantasy books with real-life history woven into them, and you actually enjoy reading about characters drinking tea, and you tend to enjoy books about people and ideas more than books mostly about action and plot twists, I recommend this book. Some things reminded me a little of Robin Hobb's books (high praise from me): The way humor is sprinkled in,for one. The way you want to bop the main character on the head for being dense at times, for another. Anyway, I do recommend it.