(Warning: May contain slight spoilers)
To be fair I got this book as an advance and had to read it for work and the summary on the advance wasn't the greatest. It actually reminded me of a YA trashy romance novel, and I -hate- romance novels. So you can see where I'm coming from, figuring the book wouldn't be that great. In the beginning it was comparable to the Twilight series which I also really hate, with Adrian being 'untouchable and gorgeous' but that's about the only similarity aside from obvious vampire-ness that's in common.
I was pleasantly surprised by the turn of events in the book, unless you read the little blurb on the back of the book you didn't realize Adrian (the vampire-demon) was a vampire until about a quarter of the way through the book. The way in which Caitlin found about his otherness was intriguing as well and you were always waiting to see when the bad-guy would actually turn up.
Still comparing this to the Twilight series I feel this book did a far better representation of a vampire-human love interest. Adrian was far less creepy than Edward always made me feel and Adrian was more conflicted actually struggling with his responsibilities and interests in Caitlin where as Edward seemed all statue-controlling-asshole-ish to me. Caitlin was sassy and not as insecure and soft-spoken as Bella always seemed to be. Actually there was so much banter between Adrian and Caitlin that that alone made the story interesting.
I really liked this book and definitely recommend you to read this. Though - I'd wait till it comes out because the advance has a lot of spelling and grammar errors. <3