This is not a bad thing, because it upends our expectations. Imagine for example, Square Enix put out a Final Fantasy game with the fight mechanic of Call Of Duty. You'd have fun seeing how the two types of games mixed.
The story has an interesting premise. People with magic exist in the world, but they are considered criminals. They can also make a drug called Flex that will give their magic to anyone who takes them. But, as any drug user knows the better the drug, the worse the long term effects are. In this case Flex gives you a lot of good luck - but then an equal amount of bad luck when you come down.
One of the people with magic is, of course, a serial killer. So an insurance agent with a past as a magic hunting cop has to chase them do wn and try to kill them. This is where we get to the heart of the book.
Steinmetz spent months on his popular personal blog documenting the slow death of his goddaughter. And the insurance agent h as a daughter stuck in the hospital who may very well die. Steinmetz knows what that's like which makes these scenes very deep and convincing. Beyond that it goes to the heart of what this story is really about - it's a fantasy of "what would I do and how far would I go to save the life of a little girl I love?" You can easily imagine Steinmetz having just these fantasies while sitting in hospital rooms facing young death right in the face.
The bottom line: What you get is a very well written book the defies genres and has a lot of heart and soul to it. I only have two minor critiques (and a review without critiques isn't really a review at all.) I thought the multiple mentions of anal lube and the main female character liking to peg her boyfriends to be pointless and something that turned the book from one that could be shared with all ages into one that is mostly for adults. Secondly I thought the "big reveal" at the end was telegraphed a bit too much, though that may be because I've read enough Steinmetz to know somewhat the way he thinks. Either way I didnt' get quite the shock value there could have been. These are very minor critiques though of a book that is as strong as "Firestarter" era Stepen King (and King's early books were not without similar minor flaws.)