As you know, Nolan views most Batman villains as watered down Jokers.
The Riddler, from a story perspective, IS just a watered down, less interesting and imposing version of the Joker.
Nolan understands the pure essence and meaning of all the characters he has used. So he actually BOILS these characters down to their most MEANINGFUL story attributes, removing the crap, and makes them STRONGER.
In fact all his villains, including in some cases their slight alterations have all (IMO) been superior improvements. Whether from a character background perspective, a psychological perspective, a visual perspective.
Bane - VASTLY improved character from an interesting background perspective, a VASTLY improved character from an aesthetics perspective (WAY, WAY more interesting), and we've yet to see the psychology perspective but I'm sure that is a vast improvement as well. His maks almost being a muzzle for such a violent, animalistic type character. The calm of his walk and gaze a startling conflict to the BRUTALITY that lurks beneath the surface.
the Joker - VASTLY improved character from a visual perspective and psychological.
I'll explain. In the comics, the all white body works. In the real world, specifically referencing B89 ... his skin LOOKS like white makeup. You can even see it rubbing off on his shirts. So if you're bringin these comics or cartoons into the real world, with REAL people, in REAL settings ... you have to tweak them for the medium. The white makeup on the face, with the flesh toned neck makes the clown face POP even more.
Ledger's Joker wearing makeup to me is an improvement from an aesthetics perspective, and from a psychological perspective. Batman didn't "create" the Joker LITERALLY (and over simplified) by dropping him in acid. Rather it's "war paint" ... Batman's appearance in Gotham has INSPIRED freaks, that have now put the city in danger. Makes Batman feel even more a sense of regret or guilt that he has inspired such madness.
The sloppy makeup, black eyes, smeared on bright red lipstick over such a vicious scar is visually arresting and quite frankly more intimidating image. And as you can see it might be the most popular visual interpretation of the character. It has bombarded pop culture since 2007.
I like that Nolan's Joker looks dirty, dresses eccentric (not fancy), as it relfects a YOUTHFUL, and natural rebeliousness against society. I like the grungy, street feel ... as if seemingly from nowehere (akin to John Doe from Se7en) that this "wild card" just appeared from the gutters of Gotham. He looks dirty, he looks derranged, his teeth are yellow ... I like the more unkept look of the Joker. It reflects rebeliousness, crazy and chaotic nature better.
I never understood why the Joker should be potrayed, given his psychological nature of being nihlistic, as being someone who would care about societal norms such as looks and be potrayed in a physical VEIN or appealing way.
He has this giant scar, or deformity making him perpetually smiling, but he cares about looking nice? Umm, I don't get it. Being eccentric with his dress is one thing, being vein about it doesn't reflect the character's psychology to me as well as it could.
Alex from a Clockwork Orange + John Doe from Se7en + Johnny Rotten + Comic book Joker = One of the best and sickest movie villains of ALL TIME.