I never read the book, so I don't know how much difference there is, but the movie (what I remember of it) was probably geared more for someone who was just getting in to thinking about science. Just from reading your posts, I'm sure it would be old hat for you. When I watched it, I was expecting more, and I had been into science and deep thinking (well, deep for me, that is) for a while already.
I didn't know there was a movie made in 2019 called Flatland. My previous response was about an animated short called Flatland: the movie.
I think we were referring to the same thing. The story is about shapes in different dimensions and one (at least from what I recall) happens to traverse into a different dimension and is fascinated by his novel perceptions yah? In the book, there is some implicit Victorian era satire as well.
I had to do some research because I really thought we were talking about 2 different things. There are actually more than a couple of movies/shorts based on the book. The one I saw was made as an introductory short for physics, I think. It was a cartoon version, with a similar story line but much simpler, with some changes with characters. I'm pretty sure I saw it in between 2 other movies. I know that I was disappointed because I thought that I'd heard that it was a decent movie. Surely I'd heard about a different version. Anyway, don't watch the one that's only a little over 30 minutes long. It would probably be a waste of your time, unless you watch it with kids who are interestedin science, and enjoy you answering questions for them.