In The Joker graphic novel, we meet minor criminal Jonny Frost. He loses his girlfriend and joins Joker's gang, giving us a story from his viewpoint of what it's like to be side-by-side with this madman. Although not specifically labeled, the graphic novel seems to take place in an "Elseworlds" universe. It doesn't take place in the regular DC Universe. Regular Batman villains appear as slight variations of themselves: Harley Quinn is a killer stripper, Killer Croc is just a large man with alligator-type skin, and the Riddler is a feeble, crippled man who uses a question mark-shaped cane to walk. The Joker himself resembles Heath Ledger's silver screen version. 
I liked the concept of this graphic novel, but the story didn't really draw me in that much, despite spot-on craziness from the Joker himself. Usually when comic book stories are chosen to be placed in graphic novels rather than in a regular comic book, they're meant to be epic. Take, for example, The Killing Joke. Unfortunately, that's where The Joker fails. I guess I was expecting to get inside the mind of the Joker himself. Some of the recent Joker's Asylum comic book stories have been much better. They're better written, and have better artwork. 
And, speaking of, most of the illustrations in The Joker appear like rough sketches rather than completed artwork. The characters have too many jagged edges for my taste. Ironically, some of the panels are a lot more detailed and beautifully illustrated. It seems as though the artist couldn't be bothered to do the rest of the graphic novel in a similar style. When I'm paying over $10 for a single story/issue in a hardcover format, I guess I expect a bit more effort put into it. Again, see Brian Bolland's flawless art in The Killing Joke.
Skip The Joker graphic novel and head straight for the Joker's Asylum stories. You'll get much more value for your dollar.
