These are some opinions to be found in the press when this book was originally published: 

Yes, this book is pretty old, but it’s still splendid information. The method is absolutely great - no doubt you will be glad you’ve found it! There is no fluff, no sugar-coating, no false promises here! It should be remembered that in the time Checkley wrote, there was much less commercialization in the fitness domain and much less P.T. Barnum-style marketing that today is pestering this branch - while the author really knew what he was talking about and was able to communicate it well. Still, this new edition is better than the original was, at least for the modern listener! 

Why is it better? Because we added some extensive commentary based on the modern knowledge and our own pretty vast experiences. And we also removed for you most of the stuff that for the modern listener wouldn’t usually be interesting - like hararngues (absolutely justified and even much needed at that time!) against corsets and unhealthy “ladylike” postures you will (for good of for bad) never see today. So now you will be able enjoy this work, which I really can call “evergreen”, and vastly profit from it by increasing your health and well-being in a quick, simple, and effective way.