First and foremost, let me say I was groomed with Mark Hamill's Joker. That voice alone made any line spoken, Paul Dini written or not, impactful because he had a genuine love for the character.

Heath did away with a lot of the silly antics and banter that make the Joker the "clown Prince of crime". Fewer jokes, more psychotic anti-hero dribble. His Joker played on the idea that the world would be a better place if he were to kill Batman. And while he may have changed his position on this idea near the end of the film, he seemed more comfortable goating Batman into doing what he wanted, instead of letting Batman arrive at that conclusion on his own.

The Joker is a character who exists for a reason. He is the one person who can turn Batman's world completely upside down with very little interaction. Joker prefers to stay on the sidelines until the very end, letting Batman know he's responsible for what is going on but at the same time maintaining a safe distance and waiting for the final curtain to fall.

Heath's Joker was active from the opening of the movie until almost the very end. He wasn't as manipulative as the Joker tends to be, instead preferring to take matters into his own hands as often as possible. Allowing himself to get captured by the GCPD isn't something the Joker voluntarily does very often, but it worked for what Heath's Joker was trying to do. Comic book Joker has a hands on role in things he feels are important, and lets his goons do the "dirty work" so to speak. Heath didn't capture the finesse of the psychopath I'm familiar with, who would often take just as much pleasure in sending a squad of men after Batman while he detonated a bomb from miles away. The fact he gave those two boats a choice is something the real Joker would never do. At the end of the countdown, or as soon as the button was pressed, both of those boats would have been sunk. The Joker doesn't value human life enough to give people a choice. He gives people the illusion of a choice, and then laughs at the futility of their struggles.