On Writing, which is excellent. I'm a fan of horror fiction. Obviously. Even the history and study of. One of my fav classes in college was "Horror Fiction" (fittingly enough). So I figured this would be right up my alley.
Maybe it could have been if it wasn't published in the early '80s, with a focus on horror fiction over the last 30 years. Or maybe if I read this when it was first published and was familiar with all of the movies and TV shows he talked about. When I knew the movie or the book, things were good. When I didn't, (and this was often) it was boring. It started to feel like a slog and I thought about stopping a few times but by then I was so far through it I was pretty much like "Dammit, my stats aren't taking a hit cos of this."
If you are a big fan of horror movies and TV shows and books from the '50s through the '80s this might be just the thing for you. And he talks about some of the more classic writers in the horror and suspense genre (with Wilkie Collins getting a shout-out). I liked those parts, when he's discussing Frankenstein and the like. Or when he was talking about horror fiction in a more general sense, instead of discussing a specific piece of media. But so much of the time I just didn't care.
I guess I could talk more about what he wrote about, how he split up the book, but honestly, I don't want to. I don't remember a lot of the book. As I already said, if you're a big fan of horror movies especially (I feel like we spent a lot of time there) you'd probably like this. Of course if you're that big of a fan of horror stuff from this time period, it's also likely you already know about this. He provides lots of recommendations (included 100 books and 100 movies listed out in a couple appendixes) and there's a little of everything there. The book shows its age a bit, not just in the focus, but in comments that are...less than enlightened and things I would hope King doesn't think any more.
Or if you want King nonfiction, maybe just read On Writing again, because that's a really great book.