Lots of worldbuilding, done the right way, without getting in the way of plot. And what a plot. The author has so many ideas that he throws away things that would be, in other hands, whole novels, perhaps trilogies. Paraphrasing:
"Yeah, I left home and climbed a rainbow to study witchcraft in a giant school in the clouds, there I had a falling out with an evil teacher who was a life-force vampire, so I burned out his lab, and the school's faculty then tried to kill me and made me fall from heaven, but let's not talk about that now, and let's focus in this resurrecting-a-god thing.".
Also, gargoyles, vampires, pirates, witches, wizards, zombies, golems, talking horses, and pirate-vampires.
Couldn't wait to start the next one in the series.