I've studied many books about creating a campaign recently and this was the most helpful of all. It takes you by the hand and it provides information and techniques to build your campaign plot step by step, piece by piece, keeping only the things that matter the most, making the chaos of a campaign idea into a structured manageable thing. Guy's channel on youtube is also a great source of useful stuff about GMs and his way of thinking is ideal in most cases.
The book has two flaws though, bad artwork and bad design. I think that it should be revised and updated by a professional book designer, that knows how to organize content in easy-to-comprehend sections/chapters and add the right form on text (bolds, quotes, tables, headings/subheadings, sections/subsections etc). In it's current form, it's ok to read it once but very difficult to go back to or refer to something again in the future.