If you think Shakespeare is boring and incomprehensible, this may change your mind. I think it's Shakespeare's greatest tragedy: the highest are brought lowest before they find some sort of redemption; the violence is relentless, graphic and fascinating; power is abused, and the abusers and victims alike are punished equally; yet at the end of the film, there's a sense of peace bought for the ultimate price.
The acting is extraordinary from top to bottom, but I must single out Scofield as Lear, setting a horrible chain of events in motion with his vanity and arrogance, and Irene Worth as his eldest daughter (older than Scofield in life) who meets her richly deserved fate in such a bizarre way. Director Peter Brook creates a barbarous world with great assurance and a bleak Bergmanesque black and white camera, his own and his actors' extensive research and rehearsal make the dialogue crystal-clear and as sharp as a blade.