I'm a librarian who loves anime, manga, and reading a wide variety of genres.
For some reason the Charles and Anna pairing worked better and more immediately for me than the Mercy and Adam pairing. Although I've only read the this story and the first couple Alpha & Omega books, I've actually reread them, whereas I haven't felt an urge to do that with any of the Mercy Thompson books.
I still really like this story. My only issue with it is the part where Anna tells Charles she doesn't like sex and he views it as a challenge. I understood what Briggs was aiming for, but it still made me uncomfortable.