This film may not be for all audiences. For a complete fun you should have a background on 60's decade on Spain and music history. If you do, you'll be laughing for the 90 minutes of the film, not only for situations but especially for dialogues with some great great jokes, some of them using double sense of some Spanish expressions.
Hidden in the story, there are also a lot of critics to some social establishments and classes and even to famous figures of the decade. The well-known character of the Spanish "picaro" deals with it in a very funny way.
The music in the film also worth serious consideration. Even a vinyl record was release with the few songs composed for the film (some more than "based" on hits for that moment). A record that some collectors search and it's not very easy to find.
The cast is formed by legends of Spanish cinema. I find that Manuel Gómez Bur and Saza both do an incredible work in making its characters believable, but the rest of the cast is also great.
On the hole it's a great very funny film that should be watched several times to discover many of its funny details.