It contains many themes that are timeless. I especially liked Wang Lung's relationships with his family members. It really explained a lot about how Chinese families are. You can read works from a thousand years ago and recognize today's China in them.

Pearl S. Buck was a missionary kid. She grew up in China and spoke Chinese natively. Since she lived with the people, (parents basically 19th century hippies) she didn't get that walled-off expat experience most Americans get. She caught some flak for her novel back then, too.

One of the isolating factors of my own experience has been that some of the morbidly sensitive modern Chinese, especially those abroad in foreign countries, have not liked it that I have written of the everyday life of their people. In all justice to them I must say that this attitude has changed in the last two years very much, so that I have ardent friends among these, but certainly The Good Earth at first displeased many Chinese in the United States. In China itself it was accepted without dislike except that it was a foreigner who wrote it. It was often said there, "It is a book which a Chinese should have written." But among the Chinese in my own country, who felt they had the honour of their country to uphold, it made distress. They had to deny it, to criticize it, to struggle against it. This also was as astonishing to me as the letter from the Fundamentalist board member. Apparently with the simplest purpose in the world, namely, merely to write novels, surely a harmless necessity for a novelist, and without any sense of wrongdoing, I was able to infuriate an astonishingly large number of people.

-- Pearl S. Buck, "Advice to a Novelist About to Be Born" (1935)

Seriously, just read it. It's an easy read that's not too long, and you can find it on archive.org in ebook format for free. Go to the bottom to download, ignore the book image. https://archive.org/details/goodearth00buck_1