In this book, the author introduce us to BDSM world where Nic and Matt meet. 
 This is not a hardcore BDSM but more to a dynamic between Dom/sub but it is a nice read. Most of the scene include soft bondage and for the other books, the character does not use any equipment in holding their sub down. 
 Other than BDSM, the romance in my opinion is quite realistic because you can meet a baker and asked them out rather than with Will, Leo and Luke which for me is more for a fantasy.