This book of "Mastery" is really just a longer introduction. I also got the Introducing Revit 2009 book and really expected to get to know the program between the two books. The editing in the book is horrible. In one instance two whole paragraphs from the previous book are in this one word for word and have nothing to do with the exercise. It's the same concept, but a completely different exercise.
To top it all off, most of the files on the companion website conflict with the exercises going on in the book. In Chapter 20, have of the first exercise is alread done and adding detail groups resulted only in errors. It was impossible to embellish the wall section in Chapter 21 for example to match the imported detail; the wall section did not match the wall section in the book nor could I find a wall section elsewhere that did.
I hoped to have a book that would detail how to use the program and function as a reference book while learning the program until the processes became natural. I will not be returning to this book as a reference. If you need an introduction, get the first book or this book, but certainly not both (if either).