Not just a teacher - and a lot of celebrities/actors who praise him. This is as in depth as it can get. If you didn't know the man (I didn't and I guess most people outside of New York or an in depth knowledge of certain actors and their studies didn't either), now you know him.
Now as in after you watch this documentary. 2 hours which never feel boring or stretched out. This is nicely structured and well researched and edited. If you like actors and don't mind a look behind their process and a general look inside their head and feelings - this is for you. There are also certain specific events and it also shows a social (commentary) side of the man. Truly an example of someone who broke barriers and helped a lot of people (across gender, skin color and/or nationality).