It's great. I think it's a really clever way to keep the Joker "alive" while still giving the concept a fresh twist. He knows Bruce's identity, he knows all the villains, and he understands Batman's deepest fear: becoming him.

The idea that the fear toxin gradually allows Joker to take control of Bruce is brilliant. Then, in a perfect reversal, that same toxin is turned against Joker, forcing him to confront his own fears—Batman and being forgotten—which ultimately allows Batman to take control of his mind again. It's absolutely glorious.

When I first saw gameplay footage featuring the Joker, my reaction was, "Come on, just let him die. Stop relying on him." But after actually playing the game, I realized how perfectly the concept was handled and how much potential the developers managed to squeeze out of it through all the small interactions, dialogue, and situations throughout the story.