I'll repeat my opinion on the vanity/narcissism issue. I think there's an amount of flexibility that goes with it. I mean, obviously, it's an illogical and twisted sense of vanity - he thinks he looks good, but he really doesn't - he's physically a freak and he's dressed in an awful, gaudy suit. If comic Joker can find attractiveness in that, who can say that movie Joker can't find runny makeup attractive? In fact, if Heath's Joker is physically less attractive than his comic counterpart and is still just as in love with himself, that would make his delusions of grandeur even greater. But at this stage, we can't say much either way on this character trait, because we haven't seen enough. But since the rest of his personality seems intact, I think the chances are fairly good.
As far as the makeup issue goes, I was against it at first but I've since settled down, for a few reasons.
Firstly, I'm intrigued by the new avenues this change could lead to. Most notably, my theory that this Joker purposely invented himself ala Batman into something to symbolize anarchy and the great joke that is life. I think that would be a great new spin on their relationship.
Secondly, permawhite Joker will always exist in the comics and Burton's Batman (it's own flaws included). I look forward to being surprised and entertained by a new spin on the character, much for the same reason that I enjoy Elseworlds stories (though this is not anywhere close to a big enough change for me to warrant labeling it Elseworlds).
Finally, I genuinely anticipate quickly forgetting about this minor "inconvenience" by getting wrapped up in the story, and specifically, the Joker's antics. Heath seems SO The Joker to me that I can find myself easily looking past a few smudges on his face, which is ALL it amounts to, essentially, for 95% of the film.
It's like this for me - the guy earlier in the thread with the white sheets analogy; yeah, it doesn't hold up under scrutiny, but I understand and agree with what he meant. If you took Batman and The Dark Knight and cut out the Joker's origin scenes from both (though I don't think TDK even has one) and any subsequent references to it (cut out the whole "You made me!" angle, which I've always found superflous, anyway), the FACT of why Joker is white matters very little. Let me put it another way - pick up any random Joker issue. Disregard what you know about the character's history. How important does his permawhiteness factor in? In that particular story? Not much. Not much at all. It certainly didn't factor in to Joker's first appearance, which is what this movie is heavily based on. That's how I expect to react to the movie; once it moves past the point of the story where the fact that he applies makeup is relevant, I'll forget about it. I won't care. Short of seeing him completely barefaced, I'll be feelin' him as total Joker.