David Thomson

“Diane Keaton won her Oscar in Annie Hall (77, Woody Allen) doing … so little, if you come to think about it, that the award must have been tribute to her likability and to the amiable, cool tolerance exhibited by her character. "Annie Hall" was nearly an -ism in the late seventies, a way of dressing, reacting, and feeling. When people fall in love with an idea, they don't bother to check how much substance it has. Being Woody Allen's best girl then seemed a very hip role; and Keaton was so deadpan cute in her basic attitudes, no matter that her way of talking became as jittery as Woody's. Even that had an edge of parody to it. She had been with Allen in [prior movies], but in Annie Hall it was as if her real self had emerged. Everyone felt good about her.

“Yet, elsewhere, in a very different mood, she had shown herself a real actress….”

David Thomson
A Biographical Dictionary of Film
Third Edition (1994), p ?