I was very glad to have been able to get this in time for the 2010 New Year holiday.
It took me about 7 hours to work through the book, split over two days.
I found the workshop-in-a-book format very appropriate to the material.
Each "day" of the workshop is split into a morning and afternoon sections and that makes for nice-sized learning chunks.
Although The Back of the Napkin: Solving Problems and Selling Ideas with Pictures was published first, and I read it first, I would recommend starting with this book. The Back of the Napkin goes into more depth about why the techniques work. This book's "hands on" workshop format gets you involved -doing- by having you practice the techniques. It is something you really need to do as well as read about.
If you aren't sure that simple pictures, as advocated in both of Dan's books, can be effective, take a look at his drawings explaining the current US health-care situation, linked from: [...]
While the level of drawing skill needed is very low, what you'll probably find is that you need to work through drawings as you are working through your understanding of your problems. Simple doesn't mean Easy, but the difficulty here is not the drawing, it is working through whatever your problem is.
My only complaint about the book is that it could use a few more blank pages.
I did the exercises in a separate notebook; I had a number of "do overs" and there just weren't going to be enough blank pages for that.