I found the Photoshop Elements x Book for Digital Photographers series of books back with Elements 2 and have purchased a copy of every version since as I've upgraded the software (why can't there be an upgrade price for the hard-copy book too). Scott Kelby and now Mat Kloskowski provide usable techniques that can be applied immediately by anyone with great results.
I also purchased the Missing Manual books for a couple of versions and while I've been satisfied, I notice that when I need some help to correct a photograph, it is to the Photoshop Elements 6 Book for Digital Photographers that I turn. In fact, I would rate the book as five stars, if it was the first version that I purchased. I do find sufficient value to purchase the new editions, but do find it is an incremental value and that the previous edition does cover the majority of the tools that you'd need, so a little less bang for the buck than if this were the only addition that I purchased, hence I've docked it one star for a 4-star rating.
The V6 edition adds significantly to the coverage of editing using the RAW editor and provides additional detail on the use of the new sharpening capabilities. The other major difference I've noticed is they've dropped from the hard-copy the chapter on Photo Restoration Techniques that was present in previous editions. They then make it available in .pdf format online as Chapter 14 in a free download.
I know some people have found the style a bit wearing at times, but it doesn't disturb me at all and the content more than makes up for the sometimes silly attempts at humor.
Over-all great book. If you only purchase one book for use with Photoshop Elements 6, make this that book and you'll be glad you did.
Bill Olsen
Las Vegas, NV