I've never been a fan of Photoshop Classroom in a Book, which I used when I first learned Photoshop seveal years ago. It presents a disjointed view of Photoshop, showing how to use various aspects of the program, but without explaining how they all work together or how the technique or feature would be used in a real-life situation. I went through it and never opened it again because I felt there had to be a better reference out there.
The best book/resource I've come across for using Photoshop to edit/restore photos is Katrin Eismann's Photosohp Restoration and Retouching. The book has dozens of photos you can download and then work on along with her as she discusses different techniques. She not only shows how each technique fits into the larger Photoshop environment, but each chapter builds on and incorporates what was learned earlier. Many retouchers/restorers consider this to be the best and most comprehensive book on the subject. If you view it on Amazon, you'll see that nearly all the sixty or so reviews speak in superlatives.
I've done restoration for several years at work, and as a hobby, and still use this book as a reference. If you are serious about using Photoshop for photo work (as opposed to fine arts), this is a book you should have, must have.