Book TW: child abuse and neglect, racism, occasional use of racial slurs common to the historical time (mid 1800’s;cht), sexism cht, problematic depiction of mental illness cht, age gap relationship 

It’s easy to see why Jane Eyre has long been a classic and holds importance to so many people. While there are certainly aspects of the book that haven’t aged well (mostly to do with language/values that are no longer appropriate to the modern reader), there are some that have aged more gracefully. Specifically, the development of Jane as a character was done remarkably well. She is dynamic and fascinating. I loved her standing up for herself, fairness, and justice even as a small child and her moral compass remains firm throughout the book. I also enjoyed her search for meaningful found family and connection throughout the book, particularly once Mrs. Fairfax and the Rivers are introduced to the story. It was also nice having a protagonist that is plain, but not (usually) concerned about it. She knows her worth and value and will not let herself be treated poorly by anyone. Her growth in the book does not dampen her spirit, rather just show her how to control (usually) and be humble and bold simultaneously. She is absolutely my favorite part of the book. I especially liked her time at school and early time at Thornfield. 
Obviously a glaring aspect of the book’s... less well aged property has to do with Jane and Mr. Rochester’s romance and the depiction of mental illness in the character of Bertha. While Jane as a female character in a classic work has an enormous amount of agency and is complex, Bertha may as well be a ghoul in the attic for all the character development she’s given. She is merely a violent obstacle in the story, given no dialogue or redeemable qualities; she is mad and that is it. Her only backstory comes from Mr. Rochester, who loathes her. I can’t give too much commentary about Bertha’s treatment that hasn’t already been stated in some form (there’s even a 1966 novel about her backstory that I plan to read someday called Wide Sargasso Sea by Jean Rhys). So I’ll leave it at just acknowledging that the plot point is more than a little troublesome, especially from a 21st century lens. Likewise, even the choice to make Mr. Rochester around 35 while Jane is only 18 was just... not the best, and it’s even commented in the story as being uncommon. Mr. Rochester is just, all around not great in my book, but I think that the book does a good job at showing Jane’s process as she falls in love/infatuation throughout the story. I just wish it hadn’t been portrayed quite so positively as it was, particularly at the end. I don’t blame Jane for falling for him, I /do/ blame Mr. Rochester for just not being honest or good for most of the story. Jane deserves better than him (in my humble opinion). But again, the character work was all done really well, they all felt like they could be real people who made those choices and led those lives; my qualms were instead the moral underpinnings Brontë was conveying through how she framed the characters. As a very minor side note, I also wish that there had been more interaction with and development of Adèle. It felt like that could have been a really strong connection (besides Rochester) throughout the middle of the story and spurred her decisions in the final part of the book, but instead everything was so focused on her infatuation with Rochester that we didn’t get to see as much of her connection to Adèle.
However, I still enjoyed the book. It was well paced and as I mentioned, the character work, especially on Jane herself was really good. I think it’s still extremely readable and engaging given its age. Particularly during Jane’s childhood, Brontë did a fantastic job making me feel keenly (and furiously) the injustices and abuse that Jane was subjected to, but it made her triumphs and wins all the more satisfying. As far as classics go, I think it holds up decently well and is still a really good fiction read as long as you are, of course, reading critically and thinking about the time/place it was written from, as we should do with any non-contemporary work. If you are a character reader especially, I think you will appreciate the story of Jane Eyre.