Soldier Boy, RUS is a collection of songs that is, as it states on the cover, intended to be "a group singing songbook". It contains a wide variety of material, including a lot of folk of many genres; everything from trad stuff like "The Broom of the Cowdenknowes" to more contemporary material like "The F-word Song". It has holiday songs, patriotic songs, some religious material, Broadway musical tunes and a limited amount of material in other languages than English. It is used (overused, IMHO) by people who are singing together for personal pleasure - I've never seen it relied upon by someone in a solo presentation, but I suppose that's possible. It's been around for a little over 20 years (original publication date was 1988). There are certainly some groups - or individuals - who use this as their only resource, which is regrettable if only because they are missing out on the vast majority of vocal music, folk or otherwise.

If a professional or semi-professional folk singer (whatever folk is, and we've pretty much agreed that is a question that shall never be answered) gets into a group whose interest is group singing, than he or she will likely be confused and irritated by the presence of, and reliance upon, this book. I guess that person has only two choices at that point: try to introduce other material (and sources) and singing style (i.e., singing from memory) or move on and try to find a group that is more suited to his or her needs. Unfortunately, the US is a big place and, outside of the East and West Coast corridors, it can be hundreds of miles from one group to another. Then there is a different two choices - get along or musical masterbation.