I've had the pleasure of listening to Dorian speak at seminars and even sharing a few brief words with him in person. When he mentioned to me that he was working on this book I had no idea how thorough and complete it would be. In fact, I remember wondering to myself how anyone could get their hands around this difficult, yet important aspect of data mining. Practitioners will immediately understand the value of this book. Those just getting started in data mining will probably have no idea how much simpler their job just became.
My only criticism of this book is that its title obscures that fact that there is a wealth of general data mining information contained within it - practical well beyond the data preparation phase. To understand why and how certain data preparation techniques work is to go a long way towards appreciating subtleties throughout the rest of the data mining process.