The great about Tarkovskij films is the poetry in the pictures, the melancholic beauty which is almost too hard to bear. A lot of it is in this one: the water, the garbage, strange, haunting sounds in the background, the dogs, the empty rooms with metal beds and rotten walls, the rain, the warmth of pure, shy love, the static, photography-like pictures (sometimes even filmed pictures), the poems, the philosophical discussions.
The failure of "Nostalghia" shows the fragility by which these ingredients are held together in films like "Solaris" or "Stalker". The thin plot line is torn apart, there is no connection between the plots of exile (what a great plot for Tarkovskij this could have been!) and the plot of saving the world by sacrifying yourself. Domenico the lunatic is just not fascinating. You feel that Andrej cannot understand Eugenia, just as Andrej the director can't. The dialogues are awfully pseudo-intellectual, the fixation on Christian faith just penetrant (compare "Stalker" which is all about faith, but without the churches) - even God himself speaks. The story of carrying a burning candle through a pool and thereby saving the world can hardly be told without exposing it to ridiculousness. Andrej's death is hardly prepared, as young and healthy as he looks this just feels like a deus ex machina. In a word, "Nostalghia" is boring and self-indulgent. Maybe it is not a good idea to name your protagonist like yourself (although there was no problem in "Andrej Rubljow") and letting him read your brother's poems. What could have been great scenes in great films look here like mere self-plagiarisms. And there are scenes where Tarkovskij's genius rises: drinking wodka in the bath arches and talking to a child (one of the few scenes where Andrej comes to life); the final scene with the candle; the scene in Domenico's house. If you have never seen a film by Tarkovskij before, don't watch this - it might keep you from seeing his masterpieces. Three stars for a blundered film in respect of the artist.