This is Lean is a high level book about lean, the philosophy of lean, not the methods and tools. The book was written by Niklas Modig, a Swedish researcher. He spends most of the book framing lean as an operational business strategy. I’m sure there is a large amount of bias from his academic experience leading to that conclusion, so I wouldn’t mind reading another book that frames lean some other way. If you’re aware of a book like that, let me know 🙂
If I had to summarize the book in a few words, I’d say it is about two types of efficiency; flow efficiency and resource efficiency. Resource efficiency is the degree to which your resources are utilized. Are your machines running all day every day? Are your programmers spending 8 hours a day writing code? Then you have 100% resource efficiency. Flow efficiency is about getting whatever you’re making done as fast as possible once cash exchanges hands. I’m am not really sure what would constitute 100% flow efficiency though, maybe a product being completed with no wait periods.