The gags are wonderful. Where Keaton's feature-length films are comparable to a band putting out a new album, his shorts feel like an EP -- just a few songs to see how people react to them.
The Balloonatic isn't about the story, but about the jokes. They feel like they're being tested for use later on down the line. The short does end on a kind of sweet and unbelievable note, but mostly it's just Keaton having fun experimenting with physical comedy.