When the movie takes a sharp left turn about 45 minutes in, the audience should know they are indeed watching a Tarantino film. The mostly silent Django (like the "D") goes through an astounding character arc on his way back to his wife but the way he gets there is entirely new. Revenge is well tread ground for Tarantino but the presentation here continues to excite. That left turn though, is what makes this revenge story different. The Brittle Brothers turn out to be the O-Ren Ishii of Django's journey.
The real villain (and star) of the story is Calvin J. Candie. He is the slimiest of the slimy. He may just be Tarantino's first real unredeemable villain. Most of the antagonists in a Tarantino story have at least one quality that makes them somewhat appealing to the audience (with maybe the exception of Stuntman Mike). Candie is just a bastion of hate, a stand-in for everything that was and is wrong with race relations in America. This makes the end of the second and the entirety of the third act hard to watch but this type of characterization is exactly what the story needs.
Certain members of the audience may look to the movie and see a satire. The humor present through out the film would provide strong evidence for this theory. An alternate theory, and one that may have been the overall intention, was to craft a Western set in the South and to tell the story of American slavery via a fairy tale. Tarantino has a well documented past of modifying history to suit his needs, always heightening things to cartoonish levels. In this case, he has modified history and retold it through the fairy tale lens. The hero is plucked from literal obscurity somewhere in Texas. He is trained in methods he will need to rescue the fair maiden. His mentor is killed and he must escape an impossible situation using those same methods and some of his own. Finally, he returns to rescue the maiden and walks through hell fire to save her. The fact that Django's wife is named after a character in a German fairy tale that mostly fits this description is obviously no coincidence, Christophe Waltz even tells this story in the movie. A fairy tale this may be, but it is certainly not a children's bedtime story.
The performances are all amazing as is to be expected. DiCaprio steals the show but Waltz is mesmerizing. Jamie Foxx turns in a stellar performance - it may just be his best non-impersonation performance to date. The dialog is quintessential Tarantino. The words are like poetry and all of the actors attack each line with aplomb. The subject matter is sensitive but the story and execution are enchanting, that makes this movie demand to be seen.