Mrs. Reed is not presented in Jane Eyre in a positive light. Mrs. Reed treats Jane terribly. She favors her own children and is abusive to Jane.
There are many indications in the first chapter that Mrs. Reed is the typical Victorian upper class woman. She eats early when there’s no company. She wears frills. However, as the story goes on we see more about the type of person Mrs. Reed is. When John harasses Jane, Mrs. Reed does nothing to stop it.
Mrs. Reed was blind and deaf on the subject: she never saw him strike or heard him abuse me, though he did both now and then in her very presence; more frequently, however, behind her back. (Chapter 1, pg. 8 in the enotes etext)
Clearly, Mrs. Reed does not treat Jane well. When Jane finally has had enough and fights back, Mrs. Reed blames Jane and not John.
Eliza and Georgiana had run for Mrs. Reed, who was gone up stairs; she now came upon the scene, followed by Bessie and her maid Abbot. We were parted: I heard the words, “Dear! dear! What a fury to fly at Master John!”
“Did ever anybody see such a picture of passion?”
Then Mrs. Reed subjoined: “Take her away to the red-room, and lock her in there.” Four hands were immediately laid upon me, and I was borne up stairs. (chapter 1, pg. 9 of the enotes etext).
Mrs. Reed is somewhat sentimental, at least regarding her deceased husband. She visits the Red Room where Jane is imprisoned in order to reminisce (not to visit Jane). She does not notice or care how terrified Jane is in the Red Room.
Mrs. Reed herself, at far intervals, visited it to review the contents of a certain secret drawer in the wardrobe, where were stored divers parchments, her jewel-casket, and a miniature of her deceased husband; and in those last words lies the secret of the red-room—the spell which kept it so lonely in spite of its grandeur.
This shows her at once both emotional and cold. She thinks of herself, but not Jane. She is selfish.
Jane herself hypothesizes over Mrs. Reed does not like her.
I know that had I been a sanguine, brilliant, careless, exacting, handsome, romping child—though equally dependent and friendless—Mrs. Reed would have endured my presence more complacently; her children would have entertained for me more of the cordiality. (chapter 2, page 12 of the enotes etext)
Jane thinks that if she had been better looking or better behaved, Mrs. Reed might have welcomed her. This demonstrates some shallowness on Mrs. Reed’s part. Since she is not directly related to Jane, she seems to consider her obligation to care for her as dying with her husband’s death.
[He] had required a promise of Mrs. Reed that she would rear and maintain me as one of her own children. Mrs. Reed probably considered she had kept this promise, and so she had, I dare say, as well as her nature would permit her; but how could she really like an interloper not of her race, and unconnected with her, after her husband's death, by any tie? (chapter 2, page 12 of the enotes etext)
So she sends Jane away to a place she has to know will be even more abusive. It demonstrates her heartlnessness.
I have included the link to the etext for chapter 1. Chapter 2 is also there by link.