I've spoken to a primary source who is a native Japanese speaker (Henry Kono Sensei). He went to O'Sensei's classes for four years. What he said is that O'Sensei would actually stand in front of the class and say emphatically "I'm not going to tell you what I'm doing."
The man changed a lot of people with his new ideas, but it seems he never really revealed the secret to what he was doing. I've also heard Saotome sensei mention that during his entire time with O'sensei he only saw him give technical pointers maybe 5 times.
If you weren't there, you can't really make a good judgement about his teaching, but you can't create such an internationally diverse practice if there is nothing there.