The Jazz Fool isn't one of the Mickey Mouse cartoons that people go 'Oh, yeah, I LOVE that one!' But then it isn't presenting itself as anything super ambitious; it's something that has some fun ideas, and is there to show Mickey having a good time at the piano. The most creative parts of this involve actually some of the other characters or, you know, 'things'; it's hard to forget the clothes that come off the hanger to dance around, or the cow who takes out its teeth and uses them as xylophone keys and proceeds to make one of the best musical moments of the whole thing.
In this short, Mickey is playing in his 'Big Show' for the animals in the audience, and plays the piano in such a way that it's practically abuse (!) By the end the piano gets its just desserts, but for the most part this short almost acts like one of the Silly Symphony shorts (or a prototype of them); just showing characters having some dilly-dallying to swinging music is enough for five minutes sometimes.