“The book is titled Buy-In with subtitle of "saving your good idea from getting shot down", and immediately this illustrates the main problem with the book - those are not the same thing at all.
The book presents a scenario (complete with cringe-inducing character stereotypes) and then shows various ways that a presentation of an idea could be attacked or derailed, and how to defend against them. Which is all well and good, and if you've ever listened to a skilled politican deflect and avoid ad hoc questioning, you'll appreciate the insight from this book which gives some of the techniques used to disarm and redirect those negative questions.
Unfortunately, deflecting and defeating attacks on your idea is not at all the same as getting buy-in for it, and the first 180 of 190 pages are devoted to the defensive tactics and only in the Appendix, which forms the last 10 pages do the authors get around to talking about the tactics for achieving buy-in.
So, good at what it does, and worth reading for that, even if the style is pretty juvenile, but it doesn't really live up to the title”