This book started off with a bang - the author did a wonderful job of pulling me in within the first paragraph. Unfortunately, the story wasn't able to maintain that level of interest throughout.
There was nothing wrong with the story- it was well-written and had an interesting, fairly unique premise. My rating is primarily based on personal preference. Two things brought this down for me:
1) I personally prefer character-driven novels. The momentum in this book comes almost exclusively from the action and storyline. I didn't dislike the MCs, but I wasn't personally invested in them either. This may just be inherent in how the story was constructed, but I would have preferred learning more about the characters' thoughts and motivations. The lack of these resulted in a book that seemed more erotica than romance, to me.
2) The BDSM seemed extraneous. I enjoy BDSM because it is often used as a catalyst for character growth and/or to provide additional insight to the character. Here, it is used solely for titillation. Again, this is just a personal preference.
Another random note- I seem to be nitpicky about the language used in romances. I prefer cock over dick, and I rather dislike the use of cunt. This is not a big enough reason to downgrade a book, but it did distract me when a distasteful word was used repeatedly. This may also have affected me because of the blunt dirty-talk way it was used, which I also tend to shy away from (yes, I know that it's a bit oxymoronic for a reader of romance novels, bit oh well- I'm claiming it nonetheless!)
In the end, if you are looking for a fast-paced, sexy, light read, you'll probably love this. It just didn't hit my hot buttons.