Luis Buñuel's approach to film-making was so unusual, and his intentions so hard to decipher, that you can never be quite sure what his movies were meant to convey. So it should probably not be too surprising that even when he makes a documentary it is still hard to tell exactly what he was doing. While this gives every initial appearance of being a straightforward documentary, it is not long before Buñuel's detailed yet surrealistic approach begins to show in subtle ways.
Whatever else may be true, it is an unusual film, and a generally interesting one. It is also unsettling - at times, very much so. It depicts a civilization that, though located in the midst of Spain just before the Franco era, could almost be from pre-historic times. Many of the images and much of the commentary are disturbing and uncomfortable to watch, to say the least. Yet the tone is far from emotional, and in fact it seems to be deliberately withdrawn, even unsympathetic, much of the time.
At the same time, it's easy to see why there are those who suggest that Buñuel was not filming a strictly objective documentary. While there are no outlandish or fantastical images, his distinctive style shows up in less obvious ways, through odd details and sequences. There also seem to be a number of different versions of the narration, which do not always cast events in the same light. So, as so often tends to be the cast with Buñuel, all that you can do is to watch it for yourself and then make your best guess as to what it all means.