I didn't hate it, it's not a bad book; it's just... very basic and obvious IMO. It felt like I was reading something I would've been really thrilled about when I was a teenager—a monster manual aimed at curious, excitable nerds instead of writers. The "150+ plot ideas" were all very clichéd, and the way the author spent pages and pages describing a demon system that a reader might just ignore completely in their own story didn't do it for me.

The movie recs were pretty good, and the appendix bit seemed useful, but that was it.