So many 5 star reviews of this book... With all due respect to the author, this is objectively NOT a 5 star book.
Frankly, it's probably not quite a 3 star book; it's doesn't quite reach "okay" status. It might be a bit better than the 2 stars I gave it, but I can't give half stars and someone has to balance out the over-inflated reviews.
For one, this novel is very poorly edited. Frequent grammar mistakes are both distracting and annoying. But I can forgive those more than the author's frequent lapses into what I can only describe as "undergraduate" level writing--something a competent editor should have caught and suggested be rewritten. Saying someone sounds "like Ms. Swan from MAD TV" is pretty lousy description; it only makes sense if you've ever seen Ms. Swan on MAD TV. If that were the only example, I'd be nitpicking, but the book is fraught with similar samples of unpracticed, unpolished writing. And once you start noticing them, it's hard to notice anything else.
The dialogue is...not especially good either, and while the characters aren't completely flat, they are, for the most part, simple archetypes who never do anything to break their molds.
But it's not all bad. The story itself has its moments, and if you like action you could pick a lot worse. Despite what some other reviewers have said, it's not particularly funny, but it is full of slavering demons and pop-culture references, so if those things make you happy, by all means get this book.
It's intended to be mindless fun, and I think it succeeds at that; I just like my mindless fun to be executed a little bit more professionally and a little less "I published this myself on the Internet."