I enjoyed this book, it was not overpowering on the romance, but it was main part of the book. Although, without the romance portion of the book I think the book would have felt incomplete. I also really liked the concept of a secret world deep underground, it's something that hasn't been explored by many fantasy/paranormal writers. The cool thing is that there really are whole societies that live under most of our major cities.
The big bad was pretty cool in this book too, they were like these mole people who have been living under our cities for many years, and they're anything but human!