I read the first copy of this book when it was in it's first edition. The gap between Media Composer and Avid Xpress has narrowed since then and the present (third) edition is much more accurate if you're an Xpress user.
The level at which this book is pitched is from introductory to intermediate and the author does an excellent job of finding the right balance. An advanced user will be using both experience and Avid's own documentation to reach those dizzying heights. But this book does an excellent job of teaching you everything you need to know from scratch.
Particularly noteworthy are the chapters on Finishing (chapter 18), Finishing on Film (chapter 19), HD and HDV (chapter 16) and using the Script Integration tool (chapter 17). Chapter 16 really helps to clear up the mess of information that abounds about HD and HDV.
At all times, the author is both frank (no shortage of opinions in this edition), informative and well-balanced in his remarks, giving a realistic picture of the job to hand. He's both independent and yet obviously biased towards the Avid software (as opposed to Final Cut Pro) - but he explains his reasons why and they seem good to me.
For PAL countries, the book occasionally slips up and fails to inform the user of the correct options or choices - lazily assuming NTSC. This means that PAL users need to work a bit harder researching the correct settings (e.g. page 325 mentions 29.97 frames per second but not 25 fps; page 273 only discusses NTSC television and not PAL).
The menu options sometimes differ from what the book says - but searching the menus does help (e.g on page 358, the Decompose tool in found in the Bin menu on Avid Xpress Pro HD and not in the Clip menu). When this happens, there's a tendency to think Xpress is a cut-down version of Media Composer. In practice I found Xpress supported everything that's in the book.
The author never fails to tell you what you really need to know to do the job properly and get started. So, in short - a fantastic book with a great CD containing clips from a well made movie for you to edit whilst training to a professional industry standard.