I found the concept of this universe incredibly interesting. The idea of vampires being slaves/employees/lovers of angels is one that I haven't seen before.

However, I found the constant "she is mine"-ing and erotic looks tiresome rather than titillating. The relationship between Raphael and Elena was telegraphed from the beginning and the consummation of said relationship wasn't exciting or climactic.

Unfortunately, the universe/world building isn't enough to keep me reading this series.