Oddly enough, I just read this book (after checking out the Tin House reprint from the library). It was surprising how many recent films have plots that come straight out of this book. It does seem a decent way for generating plots for those who have difficulty on that front and are writing plot-driven fiction, but for the sort of stuff that I write, where the plot arises more from the characters and the language, it's not all that useful (I picked it up thinking it might help with a story I've been working on that has left me stuck but it wasn't really useful for my own needs). In this instance what helped was to just keep writing and see where the characters led. I think the current draft of the story will probably be twice as long or more than the final story and sometimes that's what it takes.
The idea that there are only a small number of basic plots (ur-plots?) is not new. None other than Kurt Vonnegut wrote his master's thesis about it at University of Chicago in 1965 [0]. The exact claimed number of ur-plots is up for debate, but the idea seems sensible.
Online version: https://garykac.github.io/plotto/plotto-fm.html or https://garykac.github.io/plotto/plotto-mf.html
XML version: https://github.com/eykd/plottoxml