I thought these were horrible, until I got into rescue and volunteering at a shelter. If used correctly, they are great. I'd rather see this on a dog than a choker being used wrong, less damage to the animal, my vet gave me a demonstration.
We adopted a year old pit bull several months ago and have been to many different training who all suggested different methods to help her learn how to walk better on a leash. So far this is the collar that has worked best for her training. She responds better to this than harness walking. Only problem is that while she is a very sweet dog, she looks even more scary (than a pit bull can look to people who are not used to them) when she wears this collar as some people associate its use with bad dogs.