They were published from the 20s to the 50s and written for children, so they're quite anachronistic. I find them charming! My elementary school was discarding them 30 years ago and I claimed the whole pile.
I'm reading them to my kids now to their great enjoyment, but I've never met anyone else who's even heard of them.
I will note that I've had to explain some of the social stuff that's very much of it's time. None of the problematic stuff has been mean-spirited, but I do have to break in once or twice per book to say "we don't say things like that anymore because ..." , but my kids are used to my pointing that sort of thing out already.