This peppy mid-tempo instrumental (well, in Chicago it would be borderline up-tempo) has a lot of qualities that I think make for really fun, interesting dance music--stuff that really makes me want to swing out. Let me highlight a couple:
- The loose, laid-back timing. The song is around 185 beats per minute, but it's lazy. It doesn't feel driving or fast.
- A rapid flow of different voices. Listen to the introductory phrase, where the horns come in one after the other, and then cut out, leaving the piano to finish. None of the individual instruments solos for very long--there's a constant flow of different sounds. I think this makes it fun to dance to--there's always something new just around the corner, so if you're having trouble following or connecting with the saxophone, no worries, here comes the trumpet.
- Stop time. Super fun. Stop time is where the band halts and just plays some sort of choppy rhythm that hits on every bar or every other bar, while one instrument solos. It happens several times in this song. The first instance is after the ensemble has played the main melody phrase twice through. In the next phrase (starting around 0:32), the band goes into stop time while the clarinet (Pee Wee Russell) plays over them, then slides into a normal solo to finish the chorus. Later on there are two more stop-time phrases that follow the same pattern, first with Bud Freeman on saxophone and then Alex Hill on piano.
- Eddie Condon's guitar. In combination with the drums, he provides a lot of little rhythmic fills that make the stop-time build up, and that generally just keep things rolling along.