I know there were other circumstances to the accolades Ledger got for that, but I really didn't like that portrayal and for me it made the movie very difficult to rewatch. I felt it was inappropriately nasty and over the top, leading to a needlessly dark tone where murder and extreme violence was casual and laughed at. When people criticise cinema for glorifying violence it is this kind of movie they point at, and the choices made over The Joker both in directorion and acting brought that unsettling aspect where the camera and the movie ends up loving the villain and making the antagonist the central character (even when the antagonist couldn't possibly do what he does and instead is just a vehicle for chaos).