Historian Jelani Cobb, writing for The New Yorker, offers a critique of Django Unchained's approach to history and narrative:
Django’s behavior is so unrepentantly badass as to make him an enigma to both whites and blacks who encounter him. For his part, Django never deigns to offer a civil word to any other slave, save his love interest. In a climactic scene, Django informs his happily enslaved nemesis that he is the one n-word in ten thousand audacious enough to kill anyone standing in the way of freedom.
Is this how Americans actually perceive slavery? More often than not, the answer to that question is answered in the affirmative. It is precisely because of the extant mythology of black subservience that these scenes pack such a cathartic payload. The film’s defenders are quick to point out that “Django” is not about history.
I disagree with Cobb's take, but it's one of the smartest analyses of the movie I've read thus far, and worth your time if you're interested in the Django conversation.