I thought Jack Nicholson could have been the perfect joker if Tim Burton didn't make him so over the top crazy and likable.
I agree with the dude who posted in here that if Nicholson had played him more like his character in the shinning or after he did the shinning even. Then I think he would have been perfect.
I didn't like the face scarring either, the guy's natural smile is creepy and phsyco enough for me. He was still cool though.
I hope that TDK's version of the joker will be a bit darker and scarier than the previous incarnation was.