Five acres and independence is, fundamentally, an old book. First published in the 1920's, and then republished in the current form in the 1940's. The emphasis of the book is operating a small farm for commercial gain, something that in the modern world of the 'agribusiness' is an outdated idea. However, the basics of 'working the land' have never changed, although, such 'modern' inventions such as the tractor, as opposed to the horse do not make it into the book.
The major strength of this book is that it explains (in terms that are quite easy to understand), a lot of the basics, as to what to do and when to do it, that seem to be never written down. Anybody that has no real practical experience of working the land, and is interested in generating food for themselves should profit greatly from the book, however, it is not (although it says so throughout the book) a guide to operating a farm at a profit. There are several areas where the book is particularly strong, for example, land management, fruit and vegetable growing, and there is one major weakness, his advice on livestock, which is covered in lass than 10 pages.
Whilst other books, such as the bible of self sufficiency (John Seymour: The complete book of self sufficiency) are more modern, this book is a classic, and worth having, simply because there is a lot of sound basic advice here, although it is in no way the definitive guide.