I can't believe so many people that keep harping on this aspect and totally miss out on how it totally serves the character of django.
He was an indentured slave certainly from birth is he supposed to just drop his chains and automatically become "mr. badass"? no he needs time to find himself.
Waltz served as the mentor figure seen in so many of the old-school films in the western/samurai genre that i'm sure tarrantino loves. The figure who helps build up the hero to where he needs to go and that mentor then leaving/dying and the hero getting his justice.
Django was built up very much like a character origin film. If tarrantino was more into sequels the django character has now been set for future adventures.
No Django should not have been "instant badass" but it didn't do much to develop him as a character through out much of the film.
Shultz just has far much more to do throughout the film particularly througout most of the time spent in Candyland. His mounting frustration leading to the handshake, his emotions and motivations drive much more of the conflict of the film and receive more focus than anything relating to the internal life of Django.
Hell, Schultz even has more interaction with Broomhilda than Django does.
The film is certainly an exercise in myth-making, an origin story for the Quckest Gun in the South. I just don't think the film as a whole is entirely successful in contributing to that aim however. Rather than it being a case of a supporting character stealing the show do to a wonderful performance that out shines the principal character, this was more of a similar situation taking place at the writing stage.
There's another film that applies the mentor archetype found in Samurai and Western films. Obi-wan Kenobi certainly acts as a catalyst for Luke's journey, shows him his potential, introduces him to knew ideas and motivates him. But Obi-want is never quite so central to the action of the story, his emotions do not drive entire sections of the film and the final conflict is not dependent upon his choices. Instead, Luke now away from his life as a farmboy and with the basics of his training, Obiwan's role is reduced entirely to one of guidance, a voice to give necessary prompting, but again, not himself or his actions driving the film.
I liked the film a lot when I saw it Christmas day. I still do, but my opinion towards it has begun to cool. However problematic it may be for people racially and politically for some people, I simply have problems with the story structure and characters.