Koreeda never milks the situation for cheap sentiment, even treating the mother's departure in a merely cursory manner. This works very well, and actually makes the film sadder, as the viewer comes to care for the children in a gentle, unforced way. Although there are a few moments of laughter and amusing scenes of childish inventiveness, the film generally heads in a downward spiral, slowly yet inexorably moving towards an emotionally wrenching conclusion.

The most impressive aspect of "Nobody Knows" is undoubtedly the acting. Apart from You as the mother, Koreeda chose a group of first time actors to play the children, and all are disarmingly convincing. There is quite obviously a great deal of improvisation on display, which adds to the film's realism and sense that we are being given a genuine insight into these children's struggles. Yuya Yagira well deserved his Cannes award (over such competition as the star of "Oldboy"), with a truly astonishing performance that shows emotional range, perfectly capturing the torment of a boy forced to take on such a crushing and impossible responsibility.

Although there is obviously much to admire about "Nobody Knows", it is fair to say that the film has its faults, primarily the slow pace. Coming in at nearly two and a half hours, the film is overlong, and certainly drags during the middle. Koreeda has an incredible eye for detail, though the downside to this is that he spends a great deal of time cataloguing mundane events, and whilst this certainly makes the film realistic, it at times also makes it boring. Whilst the filmmaking technique no doubt reflects the children's situation and feelings quite accurately, it is questionable whether viewers would wish to subject themselves to a similar ordeal.

The minimalist approach may also deter some viewers, as the film mostly takes place in one room, and has little in the way of visual trappings. Although Koreeda does make full use out of the sparse locations, and plays the inherent claustrophobic nature of this to full effect, again this at times does make parts of the film seem somewhat superfluous and in need of tighter editing.

At the end of the day, these factors neatly sum up "Nobody Knows", as some viewers will find them fascinating and brave moves, whilst others will simply scratch their heads and yawn with boredom. However, for those with patience, the film comes with a high recommendation as a grueling yet fascinating and painfully realistic experience. Whether or not its success will serve to take the director's works to a wider audience remains to be seen, but for his fans the film is likely to be seen as a landmark.