My ONLY gripe about diver certifications, and I'm sure this is the case regardless of agency is that an instructor can't say "No you're not certified" or "no, you need more pool time" or "you did not pass the AOW, you got lost on the 100 foot out & back portion of the required navigation dive."
There is nothing preventing an instructor from any agency, PADI or otherwise, from keeping working with students until they are performing skills satisfactorily.
In a recent thread in which someone was making snarky comments about certain PADI procedures, I provided
this link to all the other agencies and asked him to identify any agency that did it differently. Of course, he couldn't. So when you see someone criticizing PADI as an organization, ask how any other organization is different.
A common point of mockery is the fact that PADI has a basic introductory class followed by a couple of other courses, which many say only proves that they were after more money. Can you name any agency that does it differently? In another thread in which someone talked about this the poster named another agency that he said taught one challenging class without all that followup. I almost spit my coffee on my keyboard when I read that. The agency he held up as a shining example actually has a beginning course that is less comprehensive than PADI's, followed by even more followup courses at higher costs. (The poster had, I believe, mistakenly assumed that one of the higher level courses was actually the introductory course.)
In another recent thread, someone griped about PADI's official list of specialty courses, and said another agency had a much better list, and he provided a link. he apparently had not read the lists carefully, for he failed to notice that the two were virtually the same.
There is also a lot of misunderstanding. A lot of people think that when they take courses, they are taking them from PADI, and they are paying PADI. They are not. They are taking the courses from shops and instructors who are certified to provide training that is supposed to meet PADI standards. The shops set the prices. I recently ran into a dive shop in Florida via a ScubaBoard thread that was described as charging a price for an OW course that was far above what one would expect. I didn't believe it, so I found the shop's web site and found it to be true. The price was
significantly higher than other PADI shops in the same town. Their web site did not try to hide it--they bragged that the higher price they charged was worth it because of the much more thorough degree to which they trained their divers. They made it clear that they went well above the minimum, and they were apparently being quite successful doing that. All the PADI shops in that town were offering the same certification, but the individual shops were making the decisions as to how far they were going to serve their students.
Finally, I think there is a lot of mob mentality, such as you see in a school yard when a bully attacks a kid who is a common target. Once a kid gets identified as such a target, he is soon the victim of every bully wannabe in the school. People who enjoy hurting others love those safe targets. Similarly, when people see that PADI gets bashed regularly, it is fun to jump in and join the bashing. A safe target gets picked on often.
