This film is an expressionist masterpiece ... and its overwrought, subtle-as-a-sledgehammer approach is entirely in keeping with this aesthetic. The filmmaking techniques are integral to the story being told. The darkness and despair are entirely earned, and the brutal honesty means that it all matters. Sara Goldfarb is a tragic everywoman, and Ellen Burstyn gives a shattering, monumental portrayal ... all the more surprising given how much of her story is told through distortions of camerawork. Her loss to Julia Roberts in Erin Brockovich is surely one of Oscar's most notorious injustices. This is a great film, but one that causes genuine anguish to watch.
The film is about dreams and nightmares and the transformation of the former into the latter. It's about love and the failure of love through loss of self. Addiction is just the vehicle to explore extreme variations on these themes, and it's true that Aronofsky goes where other filmmakers dare not in depicting the squalor and degradation of addiction. Any other movie on the topic seems absurdly sanitized by comparison.