Personally I think it's best to go into this film knowing as little as possible about it. The two trailers that I have seen also tell you very little about its story or themes except maybe that it has a sexual thematic and that it concerns dark family secrets, but they mostly convey the film's mood. If that's not enough for you to decide whether you want to see it or not or if you have already seen it go ahead and read on, I don't give away major spoilers.
Here's the premise: A family man jerks off to child photographs of his daughter who is by now a young adult. He also goes to prostitutes where in role plays he pretends that they are his daughter. The son finds out about this and the next time the whole family comes together (father, mother, daughter, son) he reluctantly lets the cat out of the bag. How will they react and how will everyone deal with this, most of all the father who is very ashamed of his taboo fantasies?
The title translates to "still life" although a more accurate translation in this case would probably be "silent living". The original title is very appropriate in that it isn't as much ambiguous as it is only to be taken literally, the film has nothing to do with depicting inanimate objects, rather is it referring to the film's theme of lack of communication but could also be applied to the general stillness of images in 'Stillleben'. It also reflects the film's lack of ambiguity, the little information that is given in the film throughout always neatly falls into place, it is as direct as the characters' communication is indirect and mutually avoiding of conflict.
The premise I found very interesting but the film does decidedly little with it. At not even 80 minutes the film seems very drawn out with the stillness doing little in the way of being transcendent. It starts off rather well in the way the father's perversion is slowly revealed and also in how the son "tells" his family about his discovery (he actually just one by one slips them the incriminating instruction letter that the father wrote for the prostitute). After that they pretty much all try to avoid each other and they walk and stand around by themselves to think. I've seen a lot of dead pan acting before but this one has to take the cake with actors (especially the one who plays the father) standing around for minutes on time without any expression whatsoever on their face that serves less for the viewer to project their own thoughts and emotions into than rather for it plainly depicting a void of emotion and utter cluelessness as to how to deal with the situation.
After a while it becomes tedious and I actually thought "OK, so the father is a pervert but he never acted upon his fantasies, he's a decent parent and husband, so get over it." Maybe this audience reaction was intended, there is a certain brilliance about having the initial understanding of the characters' shock turn into a lack of understanding of it because the characters are just so damn persistent with the son thinking about going to the police(!) and the father contemplating suicide. So while I obviously wasn't really convinced of the film I still more or less enjoyed it simply on the strength of its intriguing premise with the overall story feeling rather authentic even if the execution was tedious, very plain and felt somewhat empty. At least the ending, I thought, was unexpectedly poignant. Another plus is an Anja Plaschg (aka Soap&Skin) performance (playing the prostitute at the beginning) and a Soap&Skin song that was used for the end credits (which was also used in the trailers).
