The 4th edition covers NFP for preventing pregnancy under typical circumstances, as well as post-pregnancy, during menopause, and with other health issues. The latest editions have separated these into several (shorter) books. I think I prefer having all the information in one book, as a reference manual, but the current edition may be a less intimidating introduction. The 4th edition does include a chapter on how to start NFP for the first time, as well as "for beginners" sections throughout the book.
The 4th edition covers many rules for special situation that are not covered in the most recent books - things like unusual mucus patterns and temperatures patterns. All of the rules include a section on how it effects the risk of pregnancy, which is especially helpful for couples who must avoid pregnancy for serious reasons, or for couples who would like to abstain for fewer days and are comfortable with a higher chance of pregnancy.