I think I need to see the 89 film again for comparison, as that was pretty good, and I saw it a long time ago, and my impression was coloured by the sequels (which had more people in tights, but also were more ridiculous). But Dark Knight was indeed excellent.
It does a marvellous job of showing people with the batman characters' histories, but real, intriguing personalities, and is funny, and shows dark things, making gotham seem filthy, but also with uplifting moments, and neither seem forced.
( spilers )