I disagree with the previous reviewer who claims this book suffers from too many typos, etc. I've used the book for over a decade, and have found very few such errors; indeed fewer than most newer chess books. It is intelligently written and easy to follow, and includes a decent index of openings.
This slim book packs a lot of information between the covers. It's remarkably comprehensive and offers fairly deep analysis, with many partial and complete example games. The main ideas for each opening are clearly and succinctly explained, often from an original perspective. Notes to the many variations greatly enhance understanding of the salient strategic and tactical ideas.
"Chess Openings For the Average Player" is especially recommended to those looking for lesser-known but highly effective opening variations. Those rated over 1800 might want to augment this book with a more encyclopedic and up-to-date book on the openings, but for the intermediate adult player, this modest book should prove quite useful. Thank you Dover, for keeping this minor classic in print.