The film is in the style that Carne was most associated with, poetic realism. Luc Sante writes that "Port of Shadows possesses nearly all the qualities that were once synonymous with the idea of French cinema. Gabin—eating sausage with a knife or talking around a cigarette butt parked in the corner of his mouth or administering a backhanded slap to Brasseur’s kisser—is the quintessential French tough guy, as iconic a figure as Bogart playing Sam Spade. Michèle Morgan, ethereal and preoccupied, may pale a bit in comparison to some of her sisters in Parisian movies of the time (Arletty, for example), but she comes to life in bed, in a scene you can’t imagine occurring in an American movie before 1963 or so. The hazy lights, the wet cobblestones, the prehensile poplars lining the road out of town, the philosophical gravity of peripheral characters, the idea that nothing in life is more important than passion—such things defined a national cinema that might have been dwarfed by Hollywood in terms of reach and profit but stood every inch as tall as regards grace and beauty and power." Carne uses a ship-in-a-bottle and Nelly's translucent raincoat as metaphors for the sense of entrapment and ephemerality. Michèle Morgan's character falls in line with Carne's theme of androgenous women (that is further emphasized in Les Visiteurs du Soir). Throughout the film Nelly wears a beret, a trenchcoat, and walks with her head bent and hands in her pocket that is tomboyish and a variet of Gabin's uniform and gait.
Frank S. Nugent called the film "one of the most engrossing and provocative films of the season"; according to him, "it's a thorough-going study in blacks and grays, without a free laugh in it; but it is also a remarkably beautiful motion picture from the purely pictorial standpoint and a strangely haunting drama. As a steady diet, of course, it would give us the willies; for a change it's as tonic as a raw winter's day." At the time of its release, the film was widely criticized for being too negative about the State and moral character of the French, and some even blamed Carne and the film for the French losing the war to Germany.
Director Carl Dreyer included the film in his list of top ten films.
Source : Wikipedia