The book describes some of the concepts of Theory of Constraints, and how they can be applied to an Agile methodology. Ideas like small batches, controlled inventory, flow, constraints elevation among others.
If you’re not familiar with the ToC, the toyota practices, and other related trends then you can get a lot from this book. Otherwise it may seem a bit repetitive . Regardless, it’s a good guide to keep using as refresher.
Also good content about keeping quality close to the source, in particular it shows good hypothesis about unit testing and code reviews.