If you've read anything about Crash, you've probably read about its string of improbable coincidences, and its portrayal of what it means to be a racist.
Crash has some interesting twists and turns, though they would have been much more enjoyable had I not ended up in a theater full of people who were constantly, loudly, explaining things to each other. I haven't been in such a noisy theater in a long time. It was the retired crowd that was causing the majority of the problems (speaking of debunking stereotypes).
I had two issues with the movie. The first relates to the coincidences and what they do and don't show. One reading is that the coincidences help give the characters moral complexity. This is unfortunately oversimplified in the movie. People act like total jerks one minute and total angels the next minute. While that attributes more complexity to racist characters than what we've seen in films in the past, it hardly rises to the level of reality or complexity. Where is the area in between? First a cop is groping a woman of color, and later he's saving her life? If the situations had been less extreme, it would be easier to read parts of the movie as showing how racist stereotypes and attitudes are more nuanced in their connections to an individual's past than how they are usually portrayed.
The second issue is with the audience reaction to the slurs in the film. I'm not sure what this says about the film, but I was uncomfortable with the amount of belly-laughing that was going on during many of the heated exchanges between the characters. It came to a head in the latter half of the movie, when a man in front of me leaned over to tell his friend, "That's the CHINAMAN'S car," when his friend was confused about whose van was being stolen. He actually adopted the term used by a racist in the film as the best means to refer to the character.
Rather than encouraging this particular gentleman to question his stereotypes, Crash seems to have encouraged him to apply them. The "chinaman" had just been identified by name and context only moments before. So, there were several ways he could have identified the man --- by name, or "the guy in the hospital", or, "the guy who got run over", etc.
This is just one example. In the end, I had the feeling of being in the company of people laughing at a bunch of racist jokes. Maybe they were just laughing because they were uncomfortable, or because of the shock value, or because things were so over-the-top. Since the movie had some funny moments, it was hard for people to know when to laugh and when not to laugh. But I was shocked that people laughed so much, for example, at the tirade delivered by the gun store owner at the "Arab" (Persian), which included a threat to fly 747s into "their mud huts". This isn't the kind of thing you would laugh at if you heard it in person.
Abstracting from the race issues, the film does do a good job of showing the way people end up interacting in public for the few minutes they are forced to, without any concept of the context or situation that the other person is coming from, other than whatever categories come to mind. The idea that everything we see of each other in public has roots in individual histories, which we'll never be a party to, is emphasized by the film's structure --- it opens with a crime scene, flashes back to the explanation, and returns to the present.
It's hard to fault any of the acting. I think special props should go to Michael Pena, who played his heavy scenes with amazing patience. Don Cheadle was great too, and I even thought Ludacris and Larenz Tate did a good job together, though the writing behind their dialog was a little heavy-handed, fit more for a movie like Waking Life than for chit-chat between two thieves.