What a great movie experience!! The Joker was pure, insane evil. He was THE character of the movie, but that is not a bad thing. He should overshadow the quietly heroic Batman.
Harvey Dent was an arrogant white knight who couldn't live up to his own expectations...just as he should be portrayed. Lots of parallels between Harvey Dent and Batman/Bruce Wayne. Some occur to you as you watch the movie, and some hit you two days later in an "Ahhh" moment. I watched the movie before taking my 13 and 14 year old girls to make sure it was okay for them. Determined it was and took them 4 days later. Just as good the second time, if not better. Caught more of the details about the corruption the second time.
Batman was played just as he should be - a solemn, constant, unchanging figure. He is merely the thread that ties together everyone else.
And the gruesomeness you didn't see is scarier than any fake blood they could have splattered on the screen.