There's not much I can say about this film that hasn't been mentioned above, but at a risk, I will post this just because I want to share it. The film was amazing, but the effect it had on me was more incredible.
I have had a couple friends become junkies, one wound up in jail, the other is clean now. Knowledge of what happened to them in "real life", combined with the powerful montage of the four characters near the end struck a nerve. It struck a nerve big time.
When I left the theater I was shaking. I was chain-smoking. I realized that I started having an acid flashback. I had never had one before, and this one was bad. Real bad. Go nuts bad. Here's the poem that jumped out to describe what happened to me on the way home.
The train ride started doing me in
All these drunken morons, babbling their shit
I almost lost my shit
Wanted to reach and grab
Goddammit, they won't shut up
But is that all in my head
I need to go home and crash and shut it up
Just felt like sharing that. This film is amazing, just like Aronofsky's other masterpiece, Pi. Just be careful....