This is one of a number of books I read as part of my masters studies into risk management. At its core, my profession is about decisions, and in particular becoming aware of the outcomes of those decisions (whether planned or unplanned). Happily, I had just picked this up and was having a chat with one of my risk mentors when to my delight he referenced this book (he's a fan of Mr. Keeney's work).
This is, simply, one of the most applicable books on decision making that I've ever read. It shows simple techniques for thinking through alternatives (e.g. decision trees, consequence tables), and then weighing those decisions against one another in an ordered fashion.
Each concept is married to an example implementation, and each taught implementation is riddled with examples that themselves form familiar threads through the book.
It's brief, cogent, and I found it meshed very nicely with some of the other reading I've been doing of late – risk, managerial accounting, etc. If I were to write a non-fiction book, I would hope to be as effective as this one. I found it very readable, and in fact intend to read it again.