I purchased this book in the 1990's and have used his methods on two dogs. In simple terms, his technics work and he advises the use of choker chains. My response to those who have stated this is abuse to a dog and that better training methods are available. Abuse to me is a total misconception of the methods. The author doesn't tell you to continuely use extreme force. He states that a quick tug lets the dog know what is expected from his trainer. He doesn't say to haul the animal around by the throat. He explains his reason is to get the dogs attention and not kill it. Clicker training uses food and a clicker to reward a dog and I have no problem with this method but it takes longer and your dog is always expecting treats for doing as asked.
I found that using the Koehler method worked wonders and in a shorter time.Unfortunately I loaned my book out and have had to re-ordered it and look forward to using the methods again. Bottom line, his method works. Neither of the dogs I trained ever hid when the leash came out. In fact, both raced to the door, before I even had the leash attached, wanting to get going! I say this training is not abuse, if used properly. I do wish he had a more current book out though. John