Some other reviewers have claimed this movie to be uneventful - and they are right. I was not yet bored, but almost on the brink of it. What struck me most is the absence of any sort of dramatic and/or emotional climax. There is no final highlight, no real final denouement. This is not necessarily a bad thing, but here it was. Thus I cannot give the movie more than a 7, although it has lots of positive aspects to it. Let us look at them now.
Secrets of the Heart is a movie about individuals, about their daily struggles to survive and to find happiness, about their frailties and their sins. The two major themes I have detected are secrets and death, melted together in the social stratum of a lower class communal family in Spain in the early 1960s. The movie's protagonist is young Javi, a little boy. We see the world through his eyes mainly, in a naive and unaffected manner.
The theme of death is the strongest, very much linked to the theme of secrets. The death of Javi's father and the secrets his mother wants to hide from him and his brother represent the story's mysterious edge. Death and mysteries come up again when Javi and his friend Carlos want to find out about the secrets of a decayed mansion. Also the spider Javi observes in his uncle's cowshed symbolizes death, as we see it killing flies and other insects various times. So the story has indeed the capacity to provide some sort of exciting developments. It just does not fully use this capacity, and that is a pity.
The story rather focuses on a family portrayal. We get an insight look into the bleak and doleful existence of Javi's two aunts with all their imperfections and vices. The story of Javi's brother, his mother and his grandfather are presented similarly - subtle and somehow uneventful. Then again it is Javi's story, of how he grows up, how he influences and is influenced in return by the world and the individuals around him. He undergoes rites of passage and makes the story also a quest of finding out the truths about all the secrets and mysteries within his family in particular and of the world in general.
The story has its charm, but it did not exploit its full potential. It can be summarized as an authentic socio-cultural portrayal of family life, and as such it needs to be praised. However, there are too many subtle and uneventful sequences. I never felt the sort of emotional and moral attachment I normally expect from valuable movies dealing with sincere and genuine themes of life. Thus I was a bit disappointed. Those who like these sorts of cultural depictions into which you can interpret a lot and never become tired of finding new aspects by reflecting on the events will probably like it. I would have preferred some sort of real message running through the plot, some sort of dramatic climax or at least a higher pace in terms of developments.