I just saw this movie last night, and I thought it was phenomenal. Great performances all around, especially by Jamie Foxx, Samuel L., and Leo DiCaprio. Fantastic writing. If you like Tarantino movies, you'll love it. If you don't, well, you'll probably love it anyway, unless you have some aversion to lots and lots of blood. I've talked to some people who felt uncomfortable during the movie due to the subject matter or the frequent use of the n-word. I saw it in an audience that was about 50/50 white and black, and I (as a white person) didn't feel uncomfortable with the word or the humor at all, save for one scene about halfway through the movie where everyone felt uncomfortable.
For the sake of those who haven't seen it we should avoid spoilers, but which scene are you referring to? I can't remember feeling uncomfortable at all...