This film was included in the three DVD set "Saved From the Flames"--a collection of mostly ephemeral movies that have managed to avoid turning to powder, catching fire or melting--something that usually happened with the nitrate film stock used up through the 1950s.
One sort of cartoon that the Fleischer Brothers made quite a few of in the 1930s and 40s are the singalong films--shorts that certainly don't hold up very well today. After all, the idea of the audience singing along to the bouncing ball is very quaint...and archaic. As a kid, they'd occasionally put these on TV and I'd use that as a chance to get a snack or I'd just change the channel.
"Ain't She Sweet" begins in a cartoon world--cute but pretty typical of 1933 with anthropomorphic animals and black & white film. And, they all LOVE to make music. Then, after watching a few minutes of this, Lillian Roth appears in the flesh and she guides the audience in a singalong. Personally, I'd rather take a shower with a toaster. But, it is a nice window into the 1930s and is important historically--even if it isn't particularly enjoyable. The only part that piqued my interest was the end with the creatures falling into a vat of molasses and apparently dying--rather creepy, huh?!
How these sort of films ever caught on, I have no idea.