Ok, I'll say what I think about it.
This film is philosophical parable. It isn't connected with certain country and with certain time. That story could  take place anywhere. 
Zvyagintsev shows us children to whom father has returned after ten years' absence. It isn't, clear, if he was in prison or he has thrown them 10 years ago. He's trying to nurture them and to make of them the present men, and conflict arises between children and their father. Problems of children's growning-up, problems of children's psychology in general,  their first meeting with real tragedy, continious current of life and many others eternal problems are considered in this film.
Director's work impressed me very much. Zvyagintsev is indeed Tarkovsky's follower. His attention to man's psychology, participation of nature in the film referred us to Tarkovsky's masterpieces
Well, my English is rather poor, that's why it's rather difficult for me to describe all my idaes about this film. In brief? this film is worth seeing.