I love the Mercy Thompson books (and the Alpha and Omega books, the companion series), and this fourteenth book in the series lived up to my high expectations. First, warning, since some readers found this disconcerting: the book is told from the point of view of multiple characters, not just Mercy, and it has "interludes" - short chapters about things that may or may not be directly related to the plot.
Second, also as a warning, this book mostly takes Adam and Mercy out of the pack and their usual scene, so you won't see much interactions between them and the usual characters.
Third, this book is a lot of fun. It has a plot full of twists and unexpected turns, it lays out a mystery with a surprising end, it has good character development, humor, adventures. I am trying hard not to give spoilers, but it has magic, threatened end of the world, creatures from various mythologies, and complex good and bad guys (guys used in the generic sense).
I just finished it, and plan to read it again, then listen to the audio.