Tropic Thunder

I just saw Tropic Thunder, and I was a little underwhelmed by how offensive it was. After reading about all the controversy in the paper, I was expecting some really depraved shit and I didn't get it. I almost felt like the movie was in fact criticizing people who profit making movies about retarded people, and I thought what some of what they said was salient. Has this gone over everyone's heads? Is it just me? Were people paying attention to the movie, or did they get pissed and walk out when they heard a forbidden word?