The New York Times Magazine did an excellent article on "Breaking Bad" executive producer Vince Gilligan, and the twisted logic that makes the show's characters so enjoyable to watch. It's called "The Dark Art of 'Breaking Bad.'"
If the Times' online subscription technology prevents you from reading it, you can download this PDF file, which has the text but not the photos that went with the article.
The article points out that B.B. is a hit in the heartland of America, namely the Mid-West, but not so much on the two coasts. It's a "Red State" hit, you could say. Besides breaking standard TV taboos -- the heroes are meth dealers -- the writers have canned the heretofore iron-clad rule of series writing: The protagonist's character can never change. He's got to be the same person from beginning to end, or else the show's premise goes out the window. In B.B., our hero, Walt White, is the king of personality and morality disintegration. Yet we can't stop watching him.