I have read a couple of his books and I'm not fond of his methods at all.
I don't like to use physical punishment in training. Both of my dogs are very reward-oriented and, to them, punishment is only a speed-bump on the road to getting what they want. A yank on a choke chain will slow them down, but I find that it doesn't teach them much. I used to train with leash corrections and as soon as they got a correction, they'd start looking for a way around the correction that didn't involve stopping the rewarding behavior entirely. They didn't learn what I wanted them to do by trying to avoid the correction. All they learned were ways to outsmart me in order to get what they wanted. They DO learn what I want them to do by being rewarded for it.
I find that the drive for certain rewards is greater than the drive to avoid punishment. If people use punishment, it's usually just little yanks or "no"s to discourage a dog from pursuing a BIG reward (chasing a rabbit, stealing food, etc). Let's say there's a ham in front of a Labrador Retriever. The dog is straining to get to the ham, just DYING for a taste. The owner gives the leash a yank and says "no" every time he gets close to the ham. Speed bump. It slows him down a little, and might prevent him from touching the ham, but it won't take his focus off of that ham. Now, if you teach him a "watch me" command and show him that the way to get some of that ham is to pay attention to the handler? That dog's eyes won't leave his handler.
Having an obedient, attentive dog is all a matter of redirecting attention, encouraging/reinforcing good behavior and allowing the bad behavior to extinguish; I find that physical correction isn't necessary in order to achieve this.
Oh, and one other thing about physical corrections . . . This is really hard for me to explain, LOL so if it makes no sense, I apologize. With both reward and punishment, timing is important. However, even if timing is right, dogs might make associations with things that are completely irrelevant to what you are training for. I was watching my trainer work with a little Doberman puppy in Lucy's puppy class. She was teaching this pup to "leave it" and inadvertently rewarded the pup for sniffing the ground. By the end of the session, the pup was "leaving it" beautifully -- by taking her nose away from the treats and banging it on the ground repeatedly. :lol-sign: It was adorable, and eventually that was faded out when she wasn't reinforced for it.
Now, apply that to punishment. Let's say a dog jumps up on its owner. The owner yanks the dog into a "down" position for jumping up, yells "no" at it and rolls it onto its back. What if the dog doesn't apply the punishment to the act of jumping up? What if it applies the punishment to greeting its owner? Imagine the owner repeating the punishment over and over again, because the dog just isn't "getting it". The dog may be very hesitant to ever greet its owner again.
If a mistake is made in positive training, it can be remedied easily and the dog goes through no stress. If a mistake is made in punishment-based training, a dog can be ruined. I think that's what I like best about it as a novice trainer - I can screw up and the dog doesn't have to pay for my mistake.
Perhaps professional trainers can use aversives with great success, but I don't think it's a very good idea to teach novice owners/trainers to use the same methods. That's like putting a teenage driver in a racecar. Just begging for disaster.
/rant. phew.