It'll spoil nothing to tell you that at the end of Michael Clayton, there's a shot of George Clooney's face. For two minutes. Just him, looking at the camera, sitting in the back of a cab. You can interpret what's going through his head in a variety of different ways. But his ability to hold the camera, to make those two minutes magnetic and fascinating, is remarkable. The guy's really a movie star, in a way just about no other actors can match.
Beyond George Clooney's face, the movie's a lot of fun, and has some really terrific dialogue, including one of the best opening monologues I've ever heard. For more on it, read Peter Suderman's review.