From the very beginning of the book, the author has a chip on his shoulder.
Basically, Feinberg works for Crane's Stationery. Okay, fine. However, he almost immediately feels the need to discredit any etiquette maven who has said that you don't need a complete set of obscure, engraved stationery to generate proper correspondence.
However, if there's something wedding-related that you want to do in style, there's a good chance that he'll have an answer for you. Wedding, shower and party invitations; thank-you notes; reaffirmations of vows; etc. If you want to do it with engraved stock, he'll happily give you the proper way to do it. And if you happen to get that stock from Crane's, all the better, right?
Granted, the author is still a stickler for wording conventions and will give you a flat-out "No" on many current standards. Examples abound, and I believe there's a section on how to address certain political figures.
This book could be a handy reference to hand around between couples as more and more of your peers marry. Concise with a good index, the author's execuction, if not his motives, are presented quite smoothly.