I love books with a D/s relationship, especially when the sub submits so completely without the BDSM being overly hardcore. That's what we get here. And, even though I don't usually read shifter-type books, I really enjoyed this one. If you are looking for a quicky with BDSM-y shifter kink, this is a good place to be. If you are looking for deep and meaningful, this may not that book.
My major complaint is that the story ended way too soon. Minor spoiler: Gabriel and Cal struggle through the book to find the balance in their relationship and as soon as they do, its over.
The author could have taken not only the relationship between Cal and Gabriel much further but also Gabriel's integration into the pack and Gabriel's developing understanding of his power as Cal's omega.