The mood, emotional coloring or meaning, of "Miss Brill" is one of ambivalence because of shifting perspectives.
In this slice of life story, there are several instances in which there are qualifiers and exceptions added to the mention of conditions, thus mitigating the positive nature of the description. Even the opening sentence follows this pattern:
Although it was so brilliantly fine--the blue sky powdered with gold and great spots of light like white wine over the Jardins Publiques--Miss Brill was glad that she had decided on her fur.
Other sentences follow a similar pattern. For instance, Miss Brill pulls out her beloved fur, but yet calls it "Little rogue!" and notices its "sad little eyes." It is "sweet" to see it, but the nose "wasn't at all firm."
Further, when she breathes "something light and sad" moves in her bosom. Then, despite the fact that the band sounds "louder and gayer," it is the off-season and the band "didn't care" how it plays if the crowd is made of the regular attendees. When only two people occupy Miss Brill's seat, this is "disappointing" because she enjoys listening and living vicariously through the circumstances and conversations of the people who sit near her.
These shifting perspectives subtly foreshadow the somber and disappointing ending to Miss Brill's short story when she finally has a young, attractive couple, whom she envisions as a Romeo and Juliet, sit near her and destroy her illusions that she is an invisible participant in their lives. Disillusioned, she then returns home to perceive the reality of her "room like a cupboard" and the worn quality of her fur necklet that she closes into a box.