For starters, the cover is one of my all time favorite pieces of comic book imagery. In a publishing medium prone to bright colors, exaggerated physiques, and details down to the minutia, this stark view of batman silhouetted against a lightning bolt has become one of the quintessential comic book images. And this idea of Batman - one man alone against a storm - permeates the entire story. In fact, Frank Miller is generally credited as a driving force behind the transition from the Adam-West-smack!-pow! to the Batman we know and love today: Dark and grim (don't get me wrong, I love Adam West's vision of a campy goofball).
The story opens with a retired (and mustached) Bruce Wayne sharing a drink with his old friend, James Gordon. They talk about the old days in the standard Wayne/Gordon banter: Gordon pretending he doesn't know Bruce Wayne is Batman, and Bruce pretending he doesn't know that Gordon knows the truth.
Parts of the book are told through supposed media coverage, complete with social commentary from the usual politicos as well as other heroes. We see the story set in a world of media frenzy and hype, not entirely unlike our own. And our hero? The Batman we see here is almost as brutal and thuggish as the criminals he battles. He looks raw, and unformed, like a troll or ogre or some other monster, especially once he shaves that mustache. Frank Miller has channeled Daishell Hammett, George Orwell, and Hunter S. Thompson to create a truly unique story of crime, punishment (and lots of it), revenge, and justice, which stands as one of the seminal works in the graphic novel pantheon.
Read it. Love it.