Before you start to read this, please note that it will give away some of the plot. I thoroughly recommend the film, and suggest you watch it without any preconceived ideas.
This film is extraordinary with myriad levels of interest. As an insight into rural lifestyles of the era it is fascinating (it would seem German agricultural production was much more labour-intensive and much less mechanised than in Britain at the same time, although probably it's wrong to make generalisations from the depiction of events on just one estate). It clearly shows how society was stratified into aristocracy (the Baron and Baroness), the educated elite (the doctor, the pastor & the teacher) the somewhat educated higher-level servants (the steward and the nanny) with uneducated agricultural labourers at the bottom of the pack.
Visually, the film is stunning; there is tremendous attention to detail in terms of costumes and architecture (just occasionally an over-modern window frame creeps in). Time and time again, there are beautifully composed shots of the village, the fields and the estate. The interiors of the houses are particularly noteworthy. When the peasant farmer goes into his bedroom to see his just-dead wife, the bareness and unevenness of the walls is indescribably depressing. The interiors of the other homes have been recreated entirely in keeping with the station of the owner.
The two above points, however, are not the main reason for watching the film (they are sort of extra "treats", if you like). A series of sinister events leads to closer scrutiny of the characters mentioned above. The doctor is found to be exploiting the midwife in the most brutal and callous fashion, and in addition seems to be abusing his daughter (whose age - 14 - he needs reminding of); the pastor is exceptionally strict on his several children, especially in respect of sexual matters (I do not doubt he loves them, and genuinely believes he is acting in their best interests); the Baron, while perhaps not directly responsible for the death of a disabled female worker, is most certainly exploiting the very poor agricultural labourers. The women in this film are all in the shadow of their husbands and their lives fall completely into conventional roles. At one stage, the midwife tries to stand up to the doctor & the Baroness tries to stand up to the Baron (but we don't know what the outcome of their rebellions was).
Children are central to this film, and it takes some effort to untangle them and work out which belong to which parents (principally the doctor, the steward & the pastor). This creates almost a pack identity, perhaps. Some of the events are harrowing; the pastor's confrontion with Martin; when Martin asks his brothers to untie him; when Anni tells Rudi that her father has pierced her ears; when Karli is being treated by the doctor. Other scenes are touching; I found all the scenes with Eva the nanny to be just beautiful. The first time the teacher saw her, searching for a premise on which to get her to stop and talk to him, he asks if she would take a fish to his father. This is despite the facts that neither of them has anything in which to wrap the fish, and Eva does not know the teacher's father. The exchanges between the two were always beautifully scripted and never awkward. No-one in the cinema noticed the comedy turn provided by Eva's father when the teacher went to visit Eva in her own home - I think perhaps it took them off guard, given the generally dark tenor of the film.
My only "gripe" with the film would perhaps be that the voice of the narrator was very different to that of the teacher as a young man. I was nearly annoyed by the one or two longish pauses - obviously the director had his reasons for these, but I can see that some people will not like them.
There has been speculation that the film prefigures the development of national socialism in Germany. Hindsight is a wonderful thing; the film takes place around 1913/14, Hitler was elected in 1933; of these two things we are sure. Whether the three key poisonous ingredients in this film (exploitation of the poor by the rich & powerful; repression, of children in particular; male dominance of women) led directly to national socialism is not, for me, certain.