The Fleischers had a fondness for making Screen Songs out of sentimental Irish songs about New York. The best known survivor is "Sidealks of New York" and they all celebrated the common man as seen in Gotham. The genre quickly grew stale yet remained popular because the audience kept buying it. "Little Annie Rooney" was near the end of the popular phase and doesn't have much to recommend itself other than it was an excuse to put together a Screen Song.What's great about this one is the wonderful three-dimensional opening and interval just before the song. The Fleischers made a number of technological advancements in cartooning, including patents on rotoscoping, but they also adapted some and made occasional use of a cyclorama to give an immense background and permit, effectively, early multi-planing effects. The best known example is probably 1935's DANCING ON THE MOON, but it's eye-popping here.