Tom Cruise in Tropic Thunder?

I have been seeing a lot of ads for the movie "Tropic Thunder" lately. I have also been reading about how it is offending a couple of groups of people, i.e. mentally handicapped people because they use the word "retard" a lot, and black people because Robert Downey Jr. wears dark make-up to play a black man. Now I am reading that Tom Cruise has a cameo in it that is starting a comeback for him. This movie seems to be running the gamut. I was wondering if anyone has seen it (other than critics) and what their opinion is of the movie. Just wondering. If you have an opinion, please leave a comment.