It's a post-modern superhero film based off of the graphic novel by Alan Moore and Dave Gibbons. It's as much of a satire of superhero comics as it is on Cold War politics... if you were to ever read a comic book, I'd suggest it be this one.
It won the Hugo Award, is on Time Magazine's 100 Most Influencial Books of the 20th Century, and is regarded as the best graphic novel of all-time.
I greatly enjoyed it, but what do I know?
Ahh, now that you mention it, I've heard of that before and it sounds like it'd be a fairly interesting read.