This is the third movie version of Eric Kastner's oft-filmed story I've seen in the last few years. Once again, Emil, in the form of Bryan Russell, is on his way to spend the summer with his grandmother and cousin in the big city of Berlin; again, the Man In The Bowler Hat steals the money he is carrying for grandma; again, he encounters local kids, who organize and eventually bring justice.
In this Disney version, a major subplot is added (or perhaps restored; I've never read Herr Kastner's story). The Man With The Bowler Hat is involved in a bank robbery ringled by Walter Slezak. There's a nice amount of the effectiveness of gangs of children versus gangs of adults (including the stodgy and thoughtless police), with the points going to the kids; adults refuse to take them seriously at their peril.
The movie is shot in a bright and clean world that emphasizes the benign nature of reality for children, while the bank robbers toil in the grim underworld, trying to tunnel to the bank. the score by Heinz Schreiter is full of woodwinds which constantly informs the audience of the harmless silliness of this particular cinematic universe -- a mistake, I think, but what's a composer to do?
In the end, this is another pleasant version of the story, adding little to it of moment, but giving it a contemporary, 1960s air. I think the best version I've seen remains the original version, released in German in 1931, in no small part because the world in that movie is not so sunny, but the children ignore that in favor of their own constructed world.