I found this book very hard to work with. I'm convinced that the book's models and ideas have merit once they can be understood but getting that level of understanding is being very difficult. I've had colleagues also attempt to get to grips with this book to see if was just me, but all of us have had the same problem. This book explains scenarios at a reasonably understandable level for each of the examples and then dives very quickly into the abstract without a clear path of how things relate to the original problems. Other issues were the use of smalltalk for examples (smalltalk may be a fine language, but it's hardly intuitive for c,java or vb programmers), and the decision not to use UML for diagrams.