If you can afford to buy the product then buying this book will hurt very little and help quite a lot.
As I lashed out and spoilt myself by buying a copy of Photoshop 5.0 I need material to help me master this awesome graphics package. (My only regret is that Adobe do not provide any form of crossgrade offer because Photoshop is so much better than products such as Corel's Photopaint that I would recommend it to all, but the cost makes it a substantial investment and therefore generally for professionals only) As this book is essentially a reference book I will have to let you know next year how useful I have found it. At the moment it sits on my desk and is regularly thumbed when I am preparing such things as a C Vu cover or enhancing the pictures from my electronic camera.
If you can afford to buy the product then buying this book will hurt very little and help quite a lot.