Going in I was not familiar with the enormously popular children's book upon which it was based, but I have to believe the folks behind this version did a wonderful job condensing the material and preserving all the elements which helped make the book such a success. It's even a little hard to believe it was derived from a book targeted at children as the film deals with some fairly mature subject matter and has rather an adult, realistic edge. It's very impressive, certainly a meticulously crafted, heartfelt production that builds nicely to a moving conclusion. (Plus, the scenes shot in color are breathtaking.) The very visual director, Fred Wilcox, is remarkably adept at establishing mood and atmosphere through the ominous use of sets and lighting. Margaret O'Brien (repeatedly and inaccurately told in the movie how unattractive she is) who was soon to kiss childhood and stardom goodbye, is given a great part to play and is extremely appealing. (As is a very young Dean Stockwell, playing a difficult character who all too easily could've been unsympathetic.)
Also, I have to quarrel with the other post, where someone asserts that the movie is badly dated. Quite the contrary, the story zips along at a refreshingly swift pace and never lags. The movie should hardly be faulted (and in fact should be commended) for not having flashy MTV style edits every five seconds or a bombastic score. It's a very rewarding experience for both children and adults alike.