NEW YORK -- The sky crouched low and gray over Central Park, and hard little snowflakes blew against the glass doors of Woody Allen's penthouse. He once put a camera up here and photographed the New York skyline for the opening shots of his movie "Manhattan," with the lush romanticism of Gershwin's "Rhapsody in Blue" playing on the sound track. Today, something by Beethoven would have been more appropriate. He was worried about his girlfriend, Mia Farrow."Mia has this terrible thing that's been going around," Allen said, sticking his hands deep into his corduroy pockets and looking unhappily at the dark clouds. "She's been in bed for weeks. This awful flu. She's taking everything. Dristan, Advil, aspirin. I had it, too, but she has it the worst. After we finish up here, I'm going to spend the rest of the day nursing her." I had arrived at the appointed hour to talk about "Hannah and Her Sisters," Woody Allen's new movie, opening Friday in Chicago. It already is being talked about as the best movie he has ever made. I sensed that the good reviews were not going to add much cheer to the morning. This did not depress me. Woody Allen always sounds a little dubious, a little distrustful, when he is talking about cheerful things. He is at his best and most quotable when things look the worst.