As a kid, I appreciated the concept, but even at that age I was distracted by how it was essentially just an aging Jack Nicholson (starting to grow a bit of a belly) being pretty much himself.
To his credit, his spontaneous and chilling laughter freaked me out, and I loved that. I also loved the sort of disapproving quiet glares he would pass around. And the bit where he's just a silhouette with that classic hat, walking up from the shadows and speaking really creepily.
Jack was good in a lot of ways, and meh in other ways. I try to focus on the things I liked about him, but ultimately think Heath is revolutionary by comparison.
For the record, I liked the Prince stuff. Would I have liked it in Nolan's interpretation? Hell no, completely ill-fit. (Although I love how Heath's Joker quotes Frank Sinatra...) Burton sold me on it though, with his approach to the atmosphere and everything. It was a sinister, uneasy kind of silliness that I found appropriate. Especially at the parade.
I expect to be alone on that one.