One of the best movies I've ever watched, and one of the few that I could only watch once. It alternates between a gut-wrenching view of a very plausible future and scenes that have you sitting on the edge of your chair. To call it roller coaster would be an understatement.

If you haven't watched it: don't read the rest of the comments here, go watch the movie, then read the comments.

It's the best movie of my life, I watch it about once a year (that's all I can bear to do), and I see the modern world reflected from it constantly. We're living in that universe right now.

Seconding, I caught it late one night on HBO when I was a bit too young to understand what was going on and follow the plot but the movie stayed with me for many years until some time ago where I rewatched it and came to really appreciate it.