I finally figured out the problem I have with Leto's Joker. His craziness is all surface. The teeth, the tatts, the outfits. His look has all the appearance of something that's been intricately designed down to the smallest detail, which, given we're talking about the personification of chaos here, seems to miss the point by several miles.
Hmm... I haven't seen the movie yet, but just speaking of the Joker in general, I'm not sure I'd agree. A lot of the Joker's schtick has always been about performance and image. He is based on a clown, after all. He sees his crimes and acts of chaos as comedy performances for a captive audience. The very first Joker story (retold various times, the best-known of which is "The Laughing Fish") had him cutting into the radio (or TV) broadcasts to announce his upcoming murder-robberies, thereby giving the police every chance to protect the victims, but still getting away with the crimes anyway because he'd meticulously prepared for them in advance (for instance, giving the first victim a slow-acting poison and swapping out his diamond for a fake the day before, so that the crime was already done when he announced that it would happen that night).
So yes, the Joker wants to
create chaos, but his own methods are far from chaotic. He plans his crimes meticulously and with intricate calculation and skill, which is why he's such an equal match for a genius like Batman. And he's just as calculating with his image, his public persona. He's a narcissist who thrives on attention. So he cares very much about his surface image. Even Ledger's Joker was all about presentation -- his white face and green hair were actually makeup rather than the result of acid exposure, and though he allowed his makeup and hair to get smeared, that in itself was a calculated part of the anarchic performance he was putting on for the public, part of the facade of chaos he put on even though he clearly had to employ intricate advance planning and military-level skills to pull off his "chaotic" acts of terrorism.
Now, if Leto's Joker has nothing beneath the surface, then yes, that is a failure on the filmmakers' part. But having a calculated surface persona is very true to the Joker.
I really liked Leto-Joker but my main problem with him is that he seems to legitimately love and feel concern for Harley, rather than treat her as a disposable object. Remember in the Batman TAS episode where Harley had to help Bats stop Joker's nuke, and found out that he didn't bother trying to save her from the explosion?
Characters can be reinterpreted. B:TAS's Harley was trapped in her abusive relationship, too emotionally dependent on "Mistah J" to break free; but more recent comics interpretations of Harley have presented her as a much more assertive and independent character, as well as shifting her from the role of a villain to an anarchic antihero. I gather the movie's Harley is closer to the modern comics' interpretation. So maybe making the Joker the obsessive one for a change is consistent with making Harley more autonomous.