This book is definitely a favorite of mine and I hope to read more from this author soon.
That said... there was one part (specifically one paragraph) that hit my rage-button. If there is one thing I cannot stand
it is inaccurate geology. (what can I say, being a rock-geek runs in my family) I won't go into it too much here, but suffice to say that under no circumstances would California sink into the ocean, the earthquake from that would not trigger an eruption at Mt. Rainer. Mt. Rainer would not destroy all of the West Coast, and even if all that did
somehow happen it still wouldn't destroy the world economy to the point of society collapsing. Next time take the "rocks fall, every dies" approach and smack an asteroid or two into the Earth, dear author XD One extinction-level rock would probably do the job quite nicely.
But like I said, that was literally one paragraph to explain why society had collapsed and allowed the Corporations to take over and it's easy to ignore (if you are not me. RAGE EARTHQUAKES AND VOLCANOES DO NOT WORK THAT WAY RAGE ahem)
Moving on... :D
In general this world felt very well integrated. I could see a corporation deciding to look like the 'good guys' by taking on a pseudo-religious ideology, and what better way to convince people that you are on the side of good than by having a literal Heavenly Host at your fingertips? We don't get to see a lot (or really any) or the inner workings of Heaven Corp, but over all I get the impression that they want to look "clean" and "moral", right down to suppressing all independent thought by the angels and dictating what the citizens can and can't consent to with their loved ones. (and oh, the delicious irony of Hank and Ian's D/s relationship being considered "brainwashing" while poor Gabe literally had his brain wiped by Heaven Corp and memories suppressed or destroyed along with his personality!)
In the end we discover that Heaven Corp is not good, and the demons are not bad. Instead they are both rather on the same level, despite what they may want the citizens to think. Both have good and bad points, both groups help and hurt the people who look to them. This book is all about finding a balance between the two sides, and I think it does this rather nicely.