This is the only cinematic adaptation of Mark Twain’s classic novel that I've seen (so far), but I have a feeling that this might be the best one. There not really much to say, plotwise at least: it follows the adventures (major and minor) of young scamp Tom Sawyer (Tommy Kelly). He does ordinary stuff that any boy in the 19th century would do to pass the time: fishing, wooing cute Becky, and witnessing to murder, among other things.
This opulent, technicolor production is a great visualization of the story. It helps that the cast is really good, and are near dead-ringers for the characters portrayed. Newcomer Tommy Kelly is very impressive, being both mischievous and utterly charming. Other performers that stand out are the always delightful May Robson as the eternally loving but continually irritated Aunt Polly, and Victor Jory as a very frightening Injun Joe.
This is very close to its source material, which works to the movie's advantage. Besides keeping the iconic scenes (the fence painting, the island, etc), much of the dialogue is straignt from the book, keeping Twain's humor and charm intact. It doesn't attempt to be grandiose or epic; the leisurely pace is better suited to the episodic structure, not unlike a lazy summer day.
An especially impressive aspect is the set direction by William Cameron Menzies (later, he would do Gone With the Wind's decor). There are some truly gorgeous matte painting and sound stages that take full advantage of the vibrant color palate. My favorite set has to be McDougal's Cave, where Tom and Becky get lost. It's a gargantuan labyrinth of rock, with waterfalls, stone throne, and entrance-blocking boulders. It's nightmareish, yet strangely beautiful.
And speaking of beautiful, there are also some seriously nice lighting and cinematography, the later being provided by the great James Wong Howe; I especially liked a sequence where a candle goes out, only to be replaced with moonlight.