Accessible and light-hearted, and yet varied and powerful. It works best in the context of the album, between the introspective and extended Rain Song and the rockier pieces that follow. It begins quietly on single acoustic guitar. The second time through, when more (12 string?) guitars come in, the expanded sound is rich and bright. Then in comes the full band in a straight-forward rocking feel (which at its spot on the album sounds refreshing and invigorating). Meanwhile, Page's acoustic guitar can be detected throughout the song. As the song fades out, JP's keyboards fade in to take the song out on an understated note.
This piece is an excellent example of what Zeppelin was all about: balancing heavy and light. What group can start a tune with an acoustic guitar melody, turn it into an exhuberent jam, then finish with an organ outro?