I saw this for the first time about 2 to 3 years ago. I've heard very good things, but never saw it for myself.
Eastwood plays a remarkable role as Dirty Harry, a cop who bends the rules to seek justice. Great lines, and has lots of action.
The main villain of the film is the Scorpio killer who was based on the real life Zodiac killer of San Francisco.
It's one of the best movies ever made, go see it for yourself.