As it stands today, I think a lot of the praise for the Wizard of Oz is not as much a reflection on the film itself, but in its cultural significance. The story is pretty straightforward, the characters are fairly one-dimensional, but the film was also not meant to be highly layered or complicated. But the technical innovations in the film and the memorability of the characters are what has made it such a classic film. Dorothy is a great reflection on the optimism and hopefulness of children. The scarecrow, lion, and tinman emphasis the importance of thinking, courage, and love to younger audiences, and are also fun characters to watch. "Over the Rainbow" is of course such an emotional and beautiful song. Some of Garland's later renditions of it are even more heartbreaking, as her life was extremely tragic, including the treatment she underwent during the production of "The Wizard of Oz".
Review of The Wizard of Oz
