It's a shame that this book doesn't have more reviews. I'll divide my review into comments on the delivery of the content and the actual helpfulness of it:
Delivery of Content: 5/5, a Paragon of Self-Help Writing
-Incredibly Concise Writing: Most self-help books are abound with fluff. While this book is ~200 pages, the pages are smaller than an average book and there is very little that I felt could be removed without losing value. One of the least-fluff self-help books I've ever read.
-Helpful Handbook Format: The chapters are organized so that you can easily jump to the section of a chapter that pertains to your issue while also making it easy to reference this book in the future during decisions. For example, the chapter on decision blockers has 18 sections at an average of 3 pages each so you can easily jump to the blockers most applicable to you.
Helpfulness of Content: 4.5/5
-Addresses the Root Causes of Indecisiveness: I've read a decent amount about decision making written by people with backgrounds in the business world, and while they offer helpful tactics (decision matrices, incorporating data effectively, etc.), none of them touch upon the emotional issues that Rubin does. This is a shame since the emotional issues discussed (e.g. fear of failure, perfectionist standards, prioritizing something because of what others would think not what is truly right, etc.) are powerful yet often overlooked inhibitors of decision-making.
-Written by a Psychiatrist with Actual Experience: Having a psychiatrist who consistently deals with indecisive people is nice when you consider the numerous self-help books written by "gurus" or journalists who just read up on the topic.
-Helpful 8 Step Framework: His 8-step framework for decision-making helps give you more trust in your decisions; if you know that you followed the right process, then you don't need to worry about the outcome.
-Could be Somewhat More Practical For Solutions to Emotional Problems: While this book does an exceptional job at diving into the causes of indecisiveness and offering some solutions, it could delve deeper into the pragmatic aspects of implementing a solution. For example, he spends ~10 pages discussing how developing confidence in yourself is one solution that can significantly help decision-making, but the actionable advice for how to do that is sparse. Nonetheless, I understand that entire books are devoted to topics like that and the other insights from this book definitely still help overcome indecisiveness.
Overall a great book to help you address your indecisiveness in decision-making if you find it helpful to have accurate conceptual understanding of why you act the way you do during decisions. However, since all the causes discussed are rooted deeply in emotions, there is no quick fix to this issue. But by understanding where your indecisiveness comes from, making a conscious effort to address the root cause of your indecisiveness, and applying his 8-step decision making process, it will become easier to make decisions; I've been doing those three things as I read this book and it has definitely helped!