Incredibly enjoyable and a great review of the movie here. Great performances all round, the ending was quite shocking with audible gasps from myself and the wife on the sofa.
The story of the making of the film which follows the film is well worth a watch.
Apart from that ending, I'm afraid I found it incredibly boring. Lots of jibber jabbering, on and on, for what seemed hours. However that last bit did take me by surprise.
Think you have to be in a certain mood for it, it's quite challenging in terms of the monologue and the tensions around race and the characters experience. Also being set in basically two rooms for 90% of the film lends weight to the emphasis of the dialogue. It was afterall a play.