My verdict: It's hard to believe that this won the Oscar for "Best Picture" in 1941, beating out Citizen Kane, The Maltese Falcon, Suspicion, and Sergeant York. It's long, kind of boring, and, for the most part, doesn't have a point. The different subplots (the strike at the mine, Huw losing the ability to use his legs, Huw going to school, Huw's crush on his sister-in-law Bronwyn, and especially the star-crossed romance between Angharad and the minister, Mr. Gruffydd) were supposed to unify the film under the theme of the effects of the coal mine on the Morgan family. But instead they served to give it a disjointed feel. The set design is impressive, though—John Ford created an entire village in California since WWII prevented him from filming in Wales.
Despite my disappointment with the plot, I'll admit that most of the acting is well done. Cyfartha was by far my favorite character—only he transcended the film. The actor who plays Huw looked odd. And they didn't do a very good job with his makeup. Years are supposed to have passed, but the actor looks the same age throughout the film. I also wasn't terribly fond of his narration of the film, but it did serve some purpose on a few occasions.
 See Dave Wolverton's essay "On Writing as a Fantasist", which I highly recommend.
Green Valley is by BrideValley, available at http://commons.wikimedia.org/wiki/File:Late January Green Valley - geograph.org.uk - 23220.jpg.