I've always felt that Diane Keaton's acting in that scene was overshadowed by Pacino's. If you watch it closely, you can see her agony so plainly. Because I was so absorbed by Pacino's emotions, I honestly didn't notice Keaton's until recently, but she does an excellent job.
Yes she does. And she too, does an instant emotional transformation in that scene. If you watch closely, when she looks over at Michael, it's almost as though she dismisses the pain that she is feeling as a mother and is suddenly feeling pain for Michael as he let's out his silent scream.
