Any attempt I make to describe this book is going to make it sound childish so let me start by saying this is a very well-written book with a beautiful sense of place and strong characters all around, but especially strong female characters.
Remember that as I tell you that this is a fairy tale for adults, of a sort. Adams has created a place where love conquers all and borrows heavily from Arthurian mythology to build her world of magic. I'm not quite sure why Berkley markets this as a cozy mystery; the first book of the series was certainly a murder mystery but while the last three have had murders that needed to be solved, they truly are secondary to the over-arching plot concerning the magical community.
I didn't rate this book higher purely out of personal taste: it was just too sappy for me. I'm not sentimental enough to be the target audience for this story, although I still enjoyed it. This book very much reads as though it's the last of this series. If so, it ended on a very strong loose-ends-tied-up note and I feel like the series stands complete as is.
I stand corrected, there's apparently a 5th book. It'll be interesting to see where she goes with this, after everything has come so neatly to a close.