This book is very easy to read, and focuses on kanban (Japanense visual pull system), and Kanban (Davids Organisational Change Management Strategy).
David does a great job of explaining the theory behind and practical advice on implementing all of the techniques that go with Kanban. His experience with this stuff is throughout the book and these examples help to explain the topics under discussion.
I took a lot of value out the discussion around flow, limiting WIP, bottlenecks, and the history of Kanban.
While I do not think that I would apply Kanban to teams/departments that build large features; I would certainly use it for maintenance/small feature teams. Either way the knowledge around flow, etc is very valuable.