This was an incredibly deep movie if you really pay attention to the numerous subtexts throughout, the most obvious being that white people, and the notion that they are in some way superior, is ridiculous. They are being made fun of throughout the movie, as the only white person in the film who isn't a cartoon/caricature and has some semblance of real intelligence and humanity is the German.
There is a lot of other shyt in there too, but I honestly don't have the time to go through it all. I'll just say that this movie, I believe, is a critique of race relations in America today, while depicting its ugly and irrational roots, showing us how we've gotten here. Furthermore, this film is arguing that racist white people and liberal whites, who are liberal to feel good about themselves and not because they actually understand racism, are incredibly stupid.
Plus, it's a pretty fun movie. Dicaprio really did his thing in this one.