One thing I like about the SSI manual is the "Diver's Diamond", which is probably trademarked. The diamond consists of knowledge, equipment, skill, and experience. The problem occurs when something goes wrong on a dive. The OW course can't cover every potential situation.
SkullDeformity:
Okay, I've developed a real rash reading "it's not the agency it's the instructor." Why should I have to wring my hands and worry that the instructor I've chosen is going to give me an inferior education? Why? Why do I have to police these people who should be my teachers and mentors?
I cut Skull's post down because he was going a different direction than the point I want to make. There's a minimum, the OW instructors should teach that or more. Personally I think too many take the OW course thinking it is all they need. It is the beginning not the end. At some point the individual has to seek better skills/instructors out on their own. The instructor that
taught you to drive probably isn't the one that
trains you to drive a 200 MPH lap at Indy. If it were, the 200 MPH trainer would be wasting their skill on 95% or more of their students.
String:
General open-water entry level courses are just that, a basic introduction to diving and certainly not a place to stop training or learning.
My advice to anyone learning to dive is to experience a few different agencies through the course of their training. Then you'll pick up the good parts some have to offer, recognise their bad parts and generally have a broader and more balance knowledge base.
To echo String, there are things I like and dislike about the SSI, PADI, and NAUI manuals. Continuing the training is more important than starting with any one in particular.
TSandM:
But there are some statistics that suggest that a truly sad number of people get certified to dive and never dive again, or dive for a short time and quit. And one wonders how many of those people quit because they either got frightened, or because their poor skills made diving just not be any fun for them.
There's a wash-out point in a number of human pursuits. Anxiety exceeds pleasure and they leave (including the extreme "oh my ****" experience)? Been there, done that, on to something better?
I don't know I'd call it sad. If they enjoyed it and want to move on, power to them. If they had a bad experience they were not prepared for, that's sad.
TSandM:
I don't think I would have continued diving, had I tried to get on with the skill set I had at the end of OW. I was lucky enough to run into NWGratefulDiver, an instructor who had decided to go beyond the minimum standards for his students, and I have since gone on to more rigorous and (in my personal opinion, which is my right) better training, which has rendered diving safer and more fun for me.
There's always something different with the ones that hang in there. What's the Stockdale Paradox of diving? Goal focus? Are we not afraid of drowning? Not bright enough to be afraid of drowning?

Somewhere I read that there's a control issue (i.e. by diving we increase our control over the environment).