This book All About M*A*S*H isn't "all about" M*A*S*H but written by Peggy Herz as it was, in 1975 just after Season 3 of the popular CBS-TV series M*A*S*H, it tells us a lot about the show, or at least a lot if you were there in 1975 flipping through her 92 pages.
Peggy Herz is an accomplished author who writes books about television. She numbers among her other works titles such as "The Truth about Fonzie" and "Hardy Boys and Nancy Drew".
In the first few chapters of "All About M*A*S*H", she tracks the genesis of the show, how the idea was handed to Gene Reynolds, how he tracked down Larry Gelbart and how Alan Alda was approached to be Hawkeye. She follows up with chapters recounting interviews with key members of the main cast in which we gain interesting insights into their backstory and how they got involved with M*A*S*H. Much of the biographical detail we now take for granted with the advent of the internet, but back then, her book was the first source of information that, for example, Gary Burghoff had been running an animal refuge for injured birds and his current hobby (in 1975) was fish farming.
Also covered are accounts of what goes on behind the scenes at the studios. She covers Alan Alda and his commitment to feminism and Loretta Swit's description of how it felt to be a woman working in a male-dominated studio--this was a time when Swit's costumer, a woman, was being paid less than men doing the same work. Something which Swit decided to do something about, successfully as it turned out.
Interviewing at the tail end of Season 3, Herz was able to cover the departure of McLean Stevenson and the reactions of others to it. The book is silent about the departure of Wayne Rogers because nobody knew it yet. A brief mention is made about the arrival of Harry Morgan but he was not interviewed. William Christopher and Jamie Farr were not interviewed probably because at that time they had not been elevated to the main cast.
She missed an opportunity to enquire more about the beginnings of M*A*S*H and how the transition from the 1970 MASH film was made. She captured, all too briefly, some of the earlier creative decisions about characters and casting. For example she mentions that Reynolds and Gelbart decided to merge some characters but doesn't supply the tantalizing details. Many of the other questions which have puzzled fans down the years might have been answered by her. Why was Spearchucker dropped? (We know that now.) Why was Dish dropped? And what about Knocko McCarthy who appeared, without any lines, in the Pilot but was never seen again.
Nonetheless, it is a good read which captures the thoughts of key players at a critical time in the history of the show. And remember, it was among the first, if not the first, published book about the series. If you want to separate urban myth from good information on the internet today, and if you want to properly cite and source what you write about M*A*S*H, you need this book. So it is not "all about M*A*S*H" but it was a lot then, and still a lot today.