I'm not certain that you can direct any, well, much criticism at any agency but only the intructors who taught you. A common concensus of opinion amongst us UK forum types is that the instructor is more important to your learning, improvement etc than the course itself. Afterall, diving isn't rocket science and everybody learns pretty much the same material.
People seem to pick on PADI a lot because of their teaching methods but all you need to understand in the ethos behind the training. With PADI you are taught the theory and some mechanics but it is up to the divers to flesh out that learning with experience. I liked that way of learning and it never did me any harm.
The best way to improve initialy is to dive with experienced divers ............ if you can ever get one to buddy up with you!
Oh, and practice practice practice!