A wonderful, well-presented, and clearly-thought-through approach to improv and comedy. Contains plentiful exercises as well, which makes it a good improv-practice-group guide.
Unfortunately, the book is a bit repetitive, dry, condescending, and repetitive. But if you want a solid understanding of terminology and a good framework for thinking about improv, this is a great start. I’ve never found more clear definitions and approaches to concepts like the game of the scene, crazytown, believable characters, plot, etc.
While the framework and approach here is solid and clear, it’s also limited and limiting. It’ll get you to a good place and give you good tools, but it’s not the ultimate truth nor all that’s out there.