My main problem with him is he makes people believe in the dominance theory.
http://drsophiayin.com/philosophy/dominance/?/dominance.php
http://www.apdt.com/about/ps/dominance.aspx
http://www.nonlineardogs.com/
Those are just a few links about the disproven theory.
As well as that, he uses outdated methods to train dogs. Yes I understand his methods for red-zone dogs. The ones that will be put down etc. and he wants results very fast, but then after that he should work with them with positive methods. For the ones that aren't about to be put down, positive methods will work better, for the long term. He fights aggression with aggression a lot of the time, which doesn't work well in fixing the behaviour long term. He also scares and intimidates dogs to get them to do what he wants, or in some cases just forces the dogs, while they are also still scared (like when he has pulled a few terrified dogs up into the car by their neck to try and get them over their fear. Though they never really get over the fear, they just learn that they have to do it anyway to avoid being forced up via being dragged by their collar).
His methods personally don't agree with me or my morals, especially not when there is more effective AND humane ways to train.
He is very good at the method he uses though, his timing is great, he has the patience. But it shouldn't be shown on tv. I see to many people trying to use his methods with no experience, and it doesn't turn out well. Yes they have said to not use the methods by yourself on the show, but really, you can't expect everyone to listen to the warning. Usually I would say if they don't listen to the warning, that's their fault. But it matters more to me when their going to hurt dogs because they have no experience.
Other then his horrible methods (and i know he is far from the worst of trainers, I still consider his methods bad though), he has done a lot of good things. His promoted the pitbull, his promoted shelter dogs, he's saved dogs from being put down and even though he might not use the nicest methods his heart is in the right place, and from the looks of the newer episodes he seems to be changing into a more positive trainer. I've seen him try out a few positive methods, however he hasn't learned enough about them or had much practise with them, so he often does them wrong. But he tries none the less. He promotes exercising your dog. He promotes de sexing pets. He is all around a great guy for dogs, minus method he uses.
Also I have less of an issue with the kicks he gives dogs (to be honest, some of the "kicks" shown in the video hit softer then I hit my dog in play. Then again my dog is the rough and tumble type who I could probably bash and he'd wag his tail thinking it's a game). I have more of an issue with the damage he could give to some dogs necks, and really the more emotional damage. He scares and confuses a lot of dogs, it can be kind of sad to watch some of his shows.