This is a challenging movie
The language is hard to understand. There are also numerous dialogs that have references to classical Greek literature, so you need some previous knowledge to understand this movie.
The movie is also missing the normal build-up of plot and characters. There is no background story, no introduction and no explanation. The viewer is plunged straight into the story.
The viewers understanding of the movie is determined by ones previous knowledge of the art world and historical facts.
It is also a slow movie, a long movie lacking any sort of action or humor.
Also the characters in themselves are challenging. Non of them are very likable.
And I like that.
It's so rare today to find a movie that doesn't spoon-feed it's viewers.
This movie is not for everyone, and it does have it's flaws, but I for one applaud the decision to make this movie into what it is.
It would have been so easy to turn Turner into a herolike character and revel in his successes. But instead we are meet with the man behind the painter.