It isn’t really mind blowing stuff and a lot of ideas are not new. If you are familiar with improv than a lot of the things in this book you already know and I find that this Youtube video (https://youtu.be/xBkMOsZ7KDo) by Adam Koebel tells a lot of the same stuff about getting to the table with nothing prepared way better.
Some things I also flat out disagree on. I’m truly against the idea of pushing players boundaries just so you can make a more ‘interesting’ game. I personally think describing sexual content in a RPG is a really bad idea as it can quickly come over as creepy and sexual acts in a group setting feels weird.
I also think writing in a structure as if it is a story can be quite hard if you fly completely by the seat of your pants and some moments may feel a bit random as I if you were making it up on the spot (which you are!)
I would personally advice from experience the best way to run a complete improv game (especially oneshots) is to use a rules light, narrative system (my favorites are Fate Core and Dungeon World) and come with nothing prepared at the table.
During character creation ask your players a lot of questions and generally saying ‘yes, and…’ to everything they say and what they think the adventure should be about.
Then once something has formed, take a little break and write a structure of encounters one sentence each.
Then if you want to you can write a little paragraph you narrate at the beginning of your adventure.
And that’s it.
Just keep saying ‘Yes, and…’ (unless it is something completely ridiculous or impossible but if you play with people you trust this rarely happens) to your players until the session comes to a conclusion.
I think wanting to completely improvise a session shouldn’t come at the cost of having nothing written down.