I think this book is excellent. He establishes something quite eloquent with the title alone- that cycling is an "art". Books about cycling that emphasize a kind of linear adherence to hard and fast "rules" tend to stimulate a mindset that is not flexible for the survival strategy necessary for effective urban cycling.
That you don't adhere 100% doesn't seem to be the point of the book in my opinion- I certainly wasn't 100% but I still thought it was a great book. That it gets you thinking and aware in the right way seems to be it's intention.
I believe he is a frequent poster in BF. Perhaps he'll weigh in. I recommend this book more frequently than almost any other for people looking for tips as they start commuting by bike to work.