The film itself is a bit flawed, but Diane Keaton's performance is winning, brave, and just generally perfect. When Keaton and co-star Jack Nicholson have their late in the film showdown, in which she tells him that she's heartbroken, it's difficult not to feel your own heart breaking for her, too.
Keaton's last film with Woody Allen (and her first since Manhattan if you don't count her cameo in Radio Days) only earned her a Golden Globe nomination, but it's one of her most delightful performances.
After Annie Hall, Kay Corleone is Keaton's signature role. Though she played the character in three films, the best performance of the three comes in Part II as Kay's awareness of just how compromised Michael is (and perhaps was always destined to become) drives her away from him. In a trilogy with no shortage of memorable scenes, one of the most memorable is when Kay reveals to Michael that her disgust with his lifestyle prompted her to have an abortion.
The Diane Keaton role. It really can't be overstated how excellent her performance is here, even though the role has turned out to be something of a double-edged sword - at once an amazing role and performance, but also one that locked her into a persona that defined many of her roles up to and including today.
An excellent (and Oscar nominated) performance in an all but forgotten film. Keaton's performance as a good woman staring death in the face is understated, beautiful, and never takes a wrong step.