Requiem for a Dream is one of those movies which, at first, seem like a morose decadence of human life but, after watching it a few times, resemble more like a realistic portrayal of circumstances which can lead to eventual human dissolution into "despair" (GOD I hate using that word, but it's suitable for this description). Anyway, even though it is far from the bland and overly pretentious movies that directors try to use to appeal to audiences in the conventional hackeneyed manner, the novelty value of Requiem for a Dream wears off after a while. Overall, it's a good movie, mainly for the emotional effects, but there are better.
Pi was excellent and showcased Darren Aronofsky's talents with a limited budget (similar to Kevin Smith and his first major film with Clerks).