This review regards Part I, II and III of the book, that is the first 142 pages. Implementation issues of (non)executable models are beyond my review.
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This book won't tell you about every BPMN construct and shape. And this is for a reason. In practice you do not need to use all the shapes to model business reality in a transactional way. Even if you learn The Spec by heart and are aware of all the objects, you might still be an absolute zero when it comes to USEFUL business process modeling with BPMN.
This book is a valuable work since writing about good and bad BPMN practices is not-too-common among BPMN experts. Mr Silver does not follow the rule by telling you HOW to apply (as well as misapply/underuse/overuse) the most important BPMN constructs. This book is about SENTENCES in context not WORDS without it.
Another thing Mr Silver deals with is that the model correctness alone is not enough. It is just the minimum to attain. And what about consistency, process logic, completeness and unambiguity? What about different styles of modeling or ways of arranging flow objects? THESE are also crucial matters. I am pretty sure you can't be really effective in rigorous process modeling, even if you are patient enough to go through 538 pages of BPMN 2.0 Specification (dry as dust), where you have to search through the different pages and read between the lines to fully comprehend one issue. Suppose you know all the words of Webster's International Dictionary. Ask yourself if it is enough to write a good story/article/poem. I do not think so.
Mr Silver's book tries to address all these issues. In my opinion, quite successfully. However, it would naive to think that absorbing all Mr Silver is writing about is enough to become a Certified Guru of Process Modeling with BPMN 2.0. Not guru, but you will surely gain an accurate and deep understanding of real-life BPMN.