Why Greatness Cannot Be Planned is less of a book and more of a series of blog posts. It contains a great kernel of a idea, namely goal directed behavior can be too limiting to achieve truly new breakthroughs. Therefore to really do new and great things you have to not be trying to do them. This is then explained and sold with terrible examples and mostly a lot of fluff.
The fundamental idea has validity or a nugget of truth and there is some stuff in here on how to actually put that in to practice. However, most of the book is a waste of time.