Quick disclaimer: I haven't watched this entire show, but I think I've seen enough to form a fair opinion of it. That being said, here's my opinion.
This show is a look at the life and experiences of Canadians during the late 19th century through the lens of the novel. That is, it takes inspiration from the novel including some characters and scenes, but adds a considerable amount to round out a concept of the lives of Canadians at this time. With that in mind, it ends up being a lot darker than the book, as it highlights Anne's devastating and traumatic childhood pre-Green Gables as the reason for her imagination, showing that her creation of a dream world is a coping mechanism. It introduces many characters that were not a part of the original series. To those who hoped for an "accurate" film representation, this, as well as the introduction of plot lines not previously in Anne's story, seems like blasphamy. However, I think that if you look at the series not as a word for word representation of the book on screen, which no adaptation can really do, but as a new story that attempts to explore the life experiences of Canadians during this time in the context of a reworking of Anne's story, then it works well as a show. The soundtrack and cinematography are beautiful, and the characters are portrayed pretty well. I thought that the casting was done well, and it was interesting how Anne's openheartedness in the books was portrayed in the show through her response to characters created for the show. Overall, pretty interesting as a type of adaptation.
Hot take time. I don't appreciate how adaptations think that they're making stories "realistic" by making them dark as though they are originally so oversentimental that they could never be effective as stories on their own. Stories don't need to be depressing to be historically accurate, and modern writers changing classics written by people who actually lived in that time period to make them fit our depressed contemporary mindset doesn't sit right with me. Classics are effective on their own without needing to modernize them, and acting as though it is not historically accurate for people to find joy in life because "how could anyone be happy back then before our modern advances, right?" just dehumanizes the people who experienced their real lives then and wrote about it. Of course there are challenges in everyone's lives, and those should not be discounted. But adding misfortunes to make a story seem more "accurate" when the original author did not has to be seen as taking a creative liberty not based in what the author intended for their character insomuch as they appear in the book. That is to say, if a historical author is writing a novel that is semi-autobiographical and then a modern writer takes something in it that was initially positive and makes it negative when they present the event to modern audiences because it's more "historically accurate" that way, isn't that just saying that the modern writer thinks they know better than the person who actually lived it?
I'm not neccesarially saying that Anne With an E does this, or that Anne of Green Gables is entirely historically accurate, but more that even a sentimental story like Anne's has value on its own without needing to be re-presented in a dark way for modern audiences to connect with it, and that being able to take Anne's sorrows and triumphs of everyday life seriously is important.