It is sort of a one note or one song pony and may pale in comparison to more serious subject matter documentaries.
It moves along at a fun pace with very little new footage but plenty of old clips and shots from other Hollywood features including some you would expect and a few surprises such as "True Grit" and "Thoroughly Modern Millie."
This film will not change the world and maybe it doesn't take a stand as to who really wrote the song but it is interesting and entertaining. If you can't find it in a theater it will be coming to cable soon . Sit back and enjoy it.