I bought the previous edition of this book for a trip several years ago and found it completely invaluable. With tonnes of tips and tricks of the trade, it helped us get the most out of our trip to DLP.
A return visit last year was also helped by the same copy of the book.
We are going yet again this year and I had a look at this new edition with view to updating my knowledge of the parks. I was a little disappointed...
Since this book seems to be only renewed every two years, this current edition is already vastly out of date. Because DLP has an on-going evolution unlike any other Disney park in the world, this makes it difficult to be bang up to date with information.
Since this book has been published, we are now about to begin DLP's 15th Birthday celebrations, will soon see the opening of two new rides (Crush's Coaster and Cars Race Ralley in June) with another on the way early next year (The Tower of Terror in January reportedly). This book does not even cover the Buzz Lightyear ride in any great detail nad that has been there since last April.
Saying all of this, you cannot find a better guide than this for DLP and it is certainly recommended that this book be bought before your first visit to the parks (well before if possible as it includes excellent info about booking and where to stay as well as how to prepare for your trip). I suggest augmenting this book with the accompanying website that has up to the minute info on all that is going on.