This book is not an introductory text. Indeed, it requires that you'd been in the software industry for the last years because it's a deep analysis of the Agile movement and how and why it was created, and how it has evolved and adopted by the teams and companies.
Robert Martin's vision is clear here. The Agile ideas were good. They tried to solve common problems that the development companies had all around the world. But since its release, the ideas and principles were turned into a completely different animal. And that's the impression of one of the Agile Manifesto authors.
If you read this book, you probably realize that you were already lived some of the situations described there. And probably, if you are in contact with the community, you were also read/heard about the problems of the Agile movement nowadays. I love the concepts and ideas that make Agile up, but as Robert Martin also thinks, this is a little out of control.
Agile became an industry, and now it looks like it's more important to have an extensive amount of badges and certifications, to know how to scale a thing that it's not intended to be done at scale, to not have agile practitioners but coaches that bring no real value (because they excel on the processes, but not in the engineering), or Jira haters, or... The list is very long for me. So, citing the book, "You might say that Agile has become something akin to a religion in the realm of software development".
So, I strongly recommend to read it, even if you agree or not with the ideas and conclusions. This book is a journey, from the problems that Agile tried to solve, passing into the solution proposed and how it's supposed to help and ending in what's the situation today.
For me, is a must-read and refreshing text.