The book is an interesting read. There is some good basic information, and a few nuggets, but it is more a photography display than an in-depth tome, which seems to have been their intention. There is good information for getting to the more popular areas in Sipsey and Bankhead, and there are a few hints on great locations hidden in there, such as a good waterfall site and a good wildflower site, both in the same area.
I recommend it for every Sipsey hiker. It is of most use to a beginner, but you might find something you don't know about in there. Contacting the authors can often fill in areas where they were (probably intentionally) vague about in the book.
So far, it is the best book on Sipsey, with #2 being Walking Sipsey. As far as I know, nobody has done a completely comprehensive trail guide/history/uberguide yet, but Alabama's Canyons probably comes the closest. Then again, a lot of people would prefer to keep it this way.

Get it.