I like to think of Photoshop books as falling into three categories: process books, which take you through an entire process; cookbooks, that show you how to solve certain problems or achieve certain effects; and encyclopedias that discuss Photoshop tools and processes without reference to specific pictures. "Hacking Photoshop CS2" falls into the last category.
The book contains hundreds of tips, organized into chapters like "Optimizing Performance", "Hacking Layer Masks", and "Outputting to Print". While many of the tips are the kind that you would pick up in a process book, others are of the kind that most books miss. For example, like many other books, the author shows you how to apply ratings to images in Adobe Bridge. But he also provides a tip for quicker opening in Bridge of previews stored on a CD by exporting either the cache or sidecar files to the CD. Another new tip I encountered was a method for creating a new image with the same dimensions and color mode as an open image rather than the new image default.
The question a reader will have to ask himself is whether it's worth wading through a lot of tips that may not be relevant to the reader to get to the one tip that will help him. I suspect that heavy Photoshop users will find it more useful to do so. I also note that most of the tips are probably more applicable to graphic designers than photographers.
I was a little disappointed by some of the tips that weren't in the book. For example, in the discussion of optimizing performance, the author noted the importance of additional RAM to Photoshop but he didn't mention that if Windows users add more than two GB of RAM to their computers, Photoshop will only be able to access it if the 3 GB switch is set in the boot file.
The author has also been a little sloppy. For example, in providing the location of the Photoshop preferences file in Windows, he has omitted one of the subdirectories that you must go through to get to the file.
Still, for the serious user of Photoshop, there will probably be a few useful tips that will make this book worthwhile.