How would you describe Miss Brill as she is presented at the beginning of the story?

At the beginning of the story, Miss Brill is old fashioned but whimsical.  She clearly has a ritual where she walks to the park and listens to the band play each Sunday, and she decides to wear her old fox fur, a very old fashioned accessory.  Moreover, her bygone-era formality is further indicated by her appellation: we aren't told her first name; we can only call her "Miss."  Despite her age, she is somewhat playful, thinking of her fox fur as a "little rogue."  The narrator's descriptions of her perception are also whimsical.  The band's music, the ages of the people passing by, what colors they wear: Miss Brill is thrilled by the colors and conversations and sounds.  She is quite imaginative when she begins to fantasize that they are all in a play. 

However, the narrative begins to shift when it seems that she doesn't recognize this fantasy as a product of her imagination.  Miss Brill seems to actually believe that they are in a play, that she would be missed if she failed to appear one Sunday.  At this point, she begins to seem less whimsical and more delusional, less optimistic and perceptive, and actually rather sad.