This book had the seed of a good story. Unfortunately, it was planted in a patch of tired old tropes that stifled the seed's growth. 
 I wanted to like this book. I wanted to love it. And it started out in such a promising way. The heroine, Alex, is a competent, detail-focused homicide detective who has overcome horrible trauma in her past. The hero, Aramael, is a hunting angel, who, okay, broods and reads poetry, but is framed by an interestingly bureaucratic Heaven. The bad guy is a fallen angel with a personal connection to the hero. It all has potential. And the story is structured pretty well overall, with lots of echoes and callbacks to previous events. 
 But it's absolutely full of extremely overused tropes, which I'll list below. It's not a bad book, in that I've read worse. And I'd like to read the sequel (it's definitely book 1 in a true trilogy, not a connection of sequential adventures). Mostly this is because I have hope in the author. The story visible around the edges of the tropes is a good one. If she can stop relying on them so much, the next book could be great. I'm giving this book 3 stars based partially on that hope, but I'd prefer 2.5 stars. 
 I do want to talk about those tropes, because it's quite possible they might not bother other readers as much as me. I'll list them in rough order of least-spoilerish to most-spoilerish. 
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 As You Know, Bob: For the most part, the exposition is handled all right. At one point, there's a horrible conversation straight out of Do Not Do This manuals, where one character tells another character the setting history, even though both characters already know this. This is especially annoying because later, when the protagonist is informed of the same, it's simply summed up. Missed opportunity. 
 Soul Mates: I found this incredibly annoying. I don't mind the concept of soulmates itself, but it's usually used as a shorthand to avoid any kind of actual relationship between the characters. That's what happens here. They're introduced, they shake hands, and they promptly start with the loin-tingling and a sort of increased spiritual sensitivity to each other. There is much denial that this purely physical attraction can be meaningful, possible or relevant. Later, once it's explained they're soulmates, this is accepted as 'love' without further argument. This bothered me even more because this book is pitched as urban fantasy, not paranormal romance. I was asked by the author (in a blog poll) if it would bother me that the book had no sex (it wouldn't) which meant I was shocked that at least a third of the book involved thinking about sex. Later, when the hero is listing what he loves about the heroine, the traits he lists are 'courage, vulnerability, compassion, strength'. As my housemate described it, this translates to 'willpower, being a woman, being a woman with willpower, willpower'. 
 Heroine Not Allowed To Be Awesome: This one deserves special mention, because I'm not sure if it's actually a single trope so much as a combination of tropes. Alex really does start out as an awesome, competent, thorough, compelling character. Then, not only is she told repeatedly that all her skills are useless by the hero, she actually screws things up by acting like a competent, responsible heroine. There's a brief moment where the hero considers that maybe her methods could be helpful to him, but it's pretty much washed away by loin-tingling opportunities. Poor Alex tries and tries to be competent but eventually the book wears her down and she becomes the limp ragdoll love interest she's apparently supposed to be. At the very end, she had a moment to show some of that strength and courage, but it's instantly wiped away by bad guy torture. I was reminded unpleasantly of how the author of another series claims she wasn't anti-feminist, she was anti-human. I could see the argument that a human just couldn't hold out against the Fallen Angel bad guy, but given that she had a few drops of angelic blood (revealed in the first chapter) I kept expecting that to mean something other than 'makes her into a suitable love interest for the hero'. Something. Anything. I was crushed by the end of the book, when Alex hadn't done anything except be stubborn, usually in ways that were overwhelmed or disastrous. Occasionally, when it served plot, her angelic guardians gave in to her stubborness, much like one gives into a troublesome child to expedite getting out of the grocery. 
 'Complicated Lovelife' / Annoying Love Triangle: An otherwise likable character that I initially pegged as 'will hook up with heroine's sister' is revealed to instead be a future line in the Love Polygon. I don't find this interestingly complicated. Maybe some people will. 
 Evil Twin: This is used not once but twice to complicate the plot. 
 Sex Leads to Death: A minor character that the heroine doesn't like, because she was sexy, fashionable and shallow, is introduced. Later, we see stuff from her perspective, and I quite like her; she's self-aware and she respects the protagonist. Then she's seduced by the bad guy (in a set of scenes that are totally at odds with the rest of his behavior and point of view) and then, eventually, she's murdered by him because she let the great sex interfere with her thinking. 
 Other tropes also appear, but are handled with sufficient freshness that I don't feel like they need to be listed in detail-- although when one poked its head up, I almost threw the book across the room in expectation of its use being as tired as some of the ones I list above. I was pleasantly surprised there. 
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 Finally, this: Because I was hoping for an urban fantasy police procedural with angels, a lot of the book was just boring. I think any book with Nephilim should have some thoughts on sex, given that's what Nephilim represent-- but I wasn't prepared for a book that had a bit of police procedural filling in the gaps between not-particularly-compelling romance novel. And a lot of the romance felt crammed in, inserted in scenes where it didn't seem particularly appropriate. The angels seemed like humans with wings, which was an interesting setting choice at first but by the end felt like it was just a way of making the romance novel hero more exotic. Maybe that works for other people, but I'll be hoping for more urban fantasy and less romance in the next book.