Heavy on dom-sub, sometimes without rhyme or reason (maybe that's the way the author sees it, which I suppose is valid) - just to please the male character(s) I guess. Some erotic scenes that involved piercing were done well, but were S&M and imposed on the female and not written in a way where she was heart-and-soul into it, or committed at some point in the past.
Head-in-a-cage restriction is just dumb - but that's my opinion. Also, it looks stupid. There are so much more creative ways to get to the same place.
Overall, there's probably much better out there, but this book wasn't awful.