Really excellent film - the two leading ladies give stella performance as an elderly piano teacher (with some interesting secrets left over from German war times) and as a young, brilliant, but disturbed, pianist.
The backdrop of a women's prison and its local dramas and characters is a fascinating stage as their relationship develops their pasts come influence their actions and trust is built. (And no, it is not one of those touchy, feely Hollywood set-ups, this has real depth).
The "4 minutes" the title refers to, is a film sequence which I personally found incredible, I still get gooseflesh down my back when I think back to it. The audience in the cinema I saw it spontaneously burst in to applause at the end of the 4 minutes.
All in all a thoroughly worthwhile film, although there is quite a bit of German history, some knowledge of this would be of use and I am not sure how it would translate from the original German. Some excellent comedy intersperses the intensity of the drama but all credit must go to the main actors. Really good go see it..