I Feel Fine is a popular riff-based song by Beatles which was released as a single in 1964. This one is cool because it makes use of octaves which is pretty unusual for Beatles. The octaves move up and down the neck in different positions for an interesting effect, while the chorus and bridge are very simple with an on beat rhythm. The solo is no different, keeping the similar simplicity as the rest of the song's riff driven quality. It revolves around sliding quarter notes, almost emulating a vocal quality when it fills in the space between the lyrics, allowing the guitar to play the role of the lead voice.