Of course, for some a "good teacher" is a teacher who lets you sleep in class.
No doubt about that!
I actually avoided the word "good" but I did refer to the founder's title of "Osensei" as "great teacher". Just to clarify, I meant it as a title, not a personal judgement on what constitutes a "good" or even a "great" teacher. Did he deserve that title because he had pedagogical skill or was it just for providing the subject to be studied?
By pedagogical skill I mean being able to successfully pass on what one has learned which can be measured to an extent, regardless of how "good" one thinks it is. If "good" must be used, let's do so for positive results.
In that light I would say the title O Sensei is above Shihan and sensei. Sensei would be teacher, shihan example, so O Sensei would supersede all. Not surprisingly as he developed Aikido and is at the top.
Pedagogically speaking, as I have said may times, I am not sure. I do not him personally and cannot seem to get grip on the type of man he was (with ergard to how he felt how you should learn).
I understand he made you work hard, find out yourself and went mystical whenever he (tried?) to explain stuff. Did he really prepare lessons with set goals? I really do not know, but I doubt it.
You really cannot judge that good or bad. It works for you as a student or not: you cannot change the teacher only yourself....