When I read this book, my overriding impression was that, at last, I have found a process modelling approach that I can reconcile with what I see happening in real-world processes around me.
In particular, this book addresses two areas of process modelling which are often poorly handled. Firstly, it shows how to define process boundaries based on an analysis of the business area under consideration. This is a breath of fresh air compared to the often used hierarchical decomposition approach which at worst is an arbitrary chunking of the activities within an organisation, often demarcated along the lines of traditional functional silos. Secondly, it addresses representing points of scalability within processes, the oversight of which is a common cause of business process failure (and usually highly visible to the customer).
Even if you are required to model processes using BPMN, rather than the Role Activity Diagram notation used in this book, I still recommend you read it; you will never approach process modeling in the same way again!