21 Grams is perhaps the perfect movie to watch if you are interested in amazing acting. Although the story is depressing, slow paced, and overall a tad boring, the 3 part acting expo put on by Naomi Watts, Benicio Del Toro, and Sean Penn.
The non-linear plot goes like this: one random event brings together 3 strangers. Sean Penn is a sick mathematician in need of a new heart. Watts plays a wife and mother of 2 who, it seems is perfectly content. Del Toro is the ex-con who has decided to turn his life around and dedicate his whole life to professing Christianity (even winning a new truck out of it).
The thing I really enjoy about the acting in 21 Grams is how you see both ends of each of the three. At some point, most in the beginning, they are all happy and content with their lives. Of course all 3 later fall and get involved with their own personal demons. No star is one-dimensional. All of them go through crap, and their acting reflects that.