Actually containing 11 songs, and they really aren't "demos". Although nearly every number begins with just Cash's voice and acoustic guitar or piano, they are gradually filled in with tasteful electric guitar, bass, and keys, which are too exquisite to be called unfinished demos.
Released as a single, "Sunny" reached #3 on the R&B charts, #2 on the Billboard Hot 100, and #12 in the UK. When Hebb toured with The Beatles in 1966 his "Sunny" was as well received as any Beatles tune. BMI rated "Sunny" number 25 in its "Top 100 Songs of the Century".