I was a little unsure of what I would think of Dirty Harry upon rewatching it. I mean it has been nearly 40 years since this hit the big screen and society has changed so much since then.
But I have to say in a day and age when police procedurals run on TV ad-nauseum, Inspector 71, Harry Callahan, SF Homicide division, holds up pretty well. The films are not nearly as over-the-top as I remember them, and are in fact quite believable, almost understated compared to today's cop movies.
That's not to say that Dirty Harry isn't also a window onto it's time. This first film has Harry going after 'Scorpio' a serial killer who writer John Milius no doubt based on the Zodiac Killer and the Tower Sniper (two then-recent killers who were in the media).
Overall Dirty Harry is an excellent, fast-moving, action piece with a strong protagonist. One of the best of its kind.