Classic and splendid film that is still fascinating to watch. Walter Ruttmann did not make a documentary about Berlin, although 75 after date it certainly can be considered a document about a Berlin that is no more, he composed a film that tries to catch the essence of the atmosphere of a big city. The film is a good example of the art style Neue Sachlichkeit (functionalism): it is a cross-section of Berlin's life in which every element is equally important, shown without comment and in its totality it is the expression of the joy of Berlin's life. It is not a film about the life of Berliners, it is Berlin seen as a living mechanism.
The subtitle referring to Großstadt (big city) is the key, it could have been any other city. The idea as such is not the makers' prerogative. Elsewhere the fascination with the hustle and bustle of the big city was also present as was the idea to catch this on this film and in music: e.g. Cavalcanti in France made a film about Paris and the US Ferde Grofé composed his musical suite Metropolis (1927) with New York in his mind. The irony of all these endeavours is that the film or music is abstract, but that the result is a romanticizing view.
Ruttmann made several abstract film and he refers to them in the beginning with abstract horizontal lines dissolving to rail way tracks. In my view the rest of the film is also abstract. Although we see real people and situations the brilliant editing constantly keeps the film abstract: the situation and the people in a shot are not important, important is the juxtaposition to other shots: is the composition varied enough?. Thus we see a filmic composition (in stead of a musical one) and the subtitle Symphony is just. As with every composition the theme has to be modulated to keep it interesting and it is here where the weakness of the film is. The building up from the start and elaboration up to the beginning of the afternoon is splendid, precise and exiting; but from that point it bogs down for a while: we see another shop, another street etc. without adding much to what already was. It may be that Ruttmann was aware of this, note how quickly he finishes the afternoon to continue with the night-life and then immediately all the excitement and filmic fun is back.
In an 1939 interview cameraman Karl Freund said that everything possible was filmed using only candid cameras. I have my doubts. Let's take for example the sequence of the drowning lady: how could he make an extreme close-up with a hidden camera in such a brilliant angle? (By the way: if she really tried to commit suicide, was Freund himself not only one of the gaping bystanders without doing anything to save her?) How could he foresee the right angle to film the prostitute picking up her client near the cornered shop window? Not that it matters for the quality of the film, but it proofs the old adagium: filming is deceiving.