Like "2001: A Space Odyssey", lots of people (critics included) are undoubtedly struggling to get a handle on this film. Here is an odyssey of another dimension, through shifting sands of time and perspective.
On one hand, the film is surrealistic -- it leaves many questions unanswered. It seems to purposely throw the unbelievable into our faces, like Gabriel Garcia Marquez in "100 Years of Solitude". For instance, how do the stranded women survive? What do they eat? It's a Robinson Crusoe epic without explanations.
On the other hand, the film is meticulously honest with fact and detail. The eclipse portrayed in the film was in fact observed in northern Brazil on 29 May 1919. The 7 successful photographic plates from the Brazilian expedition were fundamental in proving Einstein's theory of general (as opposed to special) relativity. Also, contrary to what another IMDb commenter has incorrectly characterized as "pseudo-scientific", one of the space-time implications of Einstein's theory is very accurately alluded to in the film.
We as viewers are left to sort out the broadly surreal from the minutely exact. We must decode the poetry of this film for ourselves. And, as with poetry, appreciation for this film will likely grow with reflection and repeated viewings.
"House of Sand" is a little jewel with hidden facets. See it on a wide screen with a good sound system to fully appreciate it.