Since it's rare for software to come with manuals anymore, it usually takes a lot of trial-and-error for me to get it do do what I want it to. Because of this, I often feel I'm overlooking software features that didn't come up otherwise. Getting a book like How to Do Everything with Adobe Acrobat X was a good way for me to discover what Acrobat X can do.
One of the most interesting things I learned from the book was the Stamp tool. This is a digital equivalent of a rubber stamps that were used on paper documents. It's one of those seemingly minor things that gets used in offices around the world, and Adobe was able to turn it into a tool in Acrobat. The book teaches about how to apply, edit, and delete Stamps, as well as creating custom ones.
Another cool tool is the Email-based Review tool. For authors and publishers, this somewhat automates the practice of sending a document out to be reviewed. I can imagine peer-reviewed journals using this in their process. Masters and doctoral candidates can use this when creating their dissertations. The person reviewing the document doesn't need to have Acrobat, but does need to have Adobe Reader.
The book is easy to read and understand - informative without being boring. I think the people who will get the most out of it are those who use Acrobat, but not on a regular basis. After learning how to do something, then forgetting it due to a lack of practice, this book can serve as a set of useful reminders.