I'm about 40 pages in and it's not remotely controversial. It's really preaching to the converted. I hate how people consider this kind of thing controversial... it's pretty great/fun so far, and i dig it, but controversial is something like Happiness or pointing your finger at something politically correct. Anyone that finds this controversial is themselves racist and living in the wrong era.
the most controversial moment in inglorious basterds was when the one German soldier proudly doesn't give any information and he is killed by the bear Jew. in that moment you can tell tarantino was making a point that these men had honor to them. I'm waiting for a moment like this in the script. all the blacks are amazing people, and the majority of the whites are total racists. both sides being two dimensional. which is fine, and fun. but a slave driver that loves a black woman/man or a black slave who helps in some way or another his slave master would be far more controversial.