Hank Haney's "Essentials of the Swing" is a great full swing golf instructional book. That fact his golf swing plan is based on a a-z set of golf principles, rather than a set of tips and tricks to temporarily cure golf swing defects, puts this book heads and shoulders over just about any other golf insturction book you would find at your nearest Barnes and Noble or Borders.
I have read over 40 golf instruction books over the past couples years and this book easily makes it into my top 5 books that I would recommend if you are serious about improving your golf swing and not just looking for a few miracle cures for your slice or hook. Ben Hogan's "Five Lessons," David Leadbetter's "The Fundamentals of Hogan," (Hogan's book dissected with suggestions for improvements), Nick Faldo's "A Swing For Life," (very much influenced by Leadbetter), Jim Hardy's "The Plane Truth for Golfer's Master Class," and Jack Nicklaus's "Golf My Way" are all books worth reading 5 times or more. Although I believe Jack's swing thoughts are a little less relevant to today's golf swing, it is still a classic and great read. I find myself gravitating towards Faldo's book most often. With this said, I would lump Hank Haney's "Essentials of the Swing" in with these as a favorite.
Where Hank makes a contribution is the discussion of the swing arc and swing plane. I thought I had a great understanding of the swing plane until I read Hank's book. The idea of keeping the shaft parallel to the swing plane established at address, but at times above the orginal angle throughout the swing, seemed simple yet a new thought not presented (or presented clearly) by other instructors. His swing model is one built without any compensations and built on sheer neutral and sound fundamentals.
Hank's next best contribution to golf swing literature is the chapter on shaping shots from left to right, right to left, high, and low. I think anyone with a moderate amount of skill can replicate these swings arcs to bring their game to the next level. I favor a fade but it is necessary to learn how to hit draws, low, and high shots to become a complete golfer.
All in all, it is great book and a must read. Once you get it in your hands, I am sure you will read it many times over, I am on my 4th reading!
-John