Liked:* The world-building is interesting and well-done. The system is based on Christian mythology but is unique.* Cain & Abel are total hotties. They're interesting characters too.* Eve is a complex and likable heroine. She does make some impetuous decisions but she never strays into Too Stupid To Live.* This is a PNR that's on the steamier side (on par with Jeaniene Frost's Night Huntress series) so if you like a hot helping of smexy with your paranormal, you'll enjoy.* There are layers of plot here, and I'm assuming they'll untangle slowly as the series continues. I like that there are larger conspiracies and people playing off one another. Keeps me guessing.Liked Less:* Cliffhanger! And a very oddly structured one too. The book starts at the end and then flashes back to the beginning of Eve's journey as a Mark (someone who bears the Mark of Cain). The plot works its way to where the book started but then doesn't resolve it. So... loopy cliffhanger! I'm personally not a fan of cliffhangers.* The whole Mark thing was sometimes confusing. When the author writes "Mark" in this book, she means someone with the Mark of Cain. I, however, kept wondering who Mark was and how I missed his entry into the scene before feeling like a total dumba$$ when I realized what she meant. It might have been wiser to refer to the Marks as something other than a common male name.* I never really got what Eve's sin was. Overall, a sexy urban fantasy read with a unique setup. I will definitely be checking out the next in the series (and probably Ms. Day's other series).