It is a compilation of ideas expressed in multiple articles written by the legend of the software craftsmanship community.
The book contains a historical overview of software development techniques. The primary goal of the book is to describe the general rules to design a software system and organize a codebase.
The book gives some necessary context for the software development process. Most of the book might be beyond comprehension.
It exposes readers to the author's wisdom gained and promotes a sensitive attitude toward software architecture. Some of the ideas might be too radical, however useful for a software developer’s purview.
More information about the book is available here.