There seem to be four major types of serious Photoshop CS books. One is the Kelby series, where you learn the absolutely quickest and most up to date way to do modern things. These books just you pick up and start to read anywhere to learn the newest tricks.
Then, there are the books that you must follow along chapter by chapter because they are really course books that uncover every tool, such as the Adobe Photoshop CS Classroom in a book series.
Next, are the philosophy books of Photoshop, such as Adobe CS for Photographers by Martin Evening and Adobe Photoshop CS Studio Techniques by Willmore and Real World Digital Photography by Eismann, et all. Those, you just read anywhere and keep on reading forever. They are rather thick and very interesting on many levels for a complete understanding of the program. Finally, there are the retouching "how to" books such as two in the Eismann series; Restoration and Retouching , Masking and Compositing. Another important genre in learning about printing and even more about color would have to include the latest books on color management techniques and digital photography.
I have about eight Photoshop books. It seems embarrassing to have so many but the program is so deep and there is a lot to learn about my favorite program. Each book has its own approach, of course and everyone has their own way of learning and remembering. I hope this is interesting to you. William Kazak
http://www.williamkazak.com 
