I have little to add to what the first two commentators have written.
Rossellini has a penchant for melodrama and rhetoric, but, fortunately, he keeps this tendency for the most part in check in this case. This film is dry and sober, and yet touching in the way it describes the transformation of a petty swindler, who manages to survive by cheating those who are unlucky enough to have their loved ones arrested by the Nazis and try everything they can in order to save them from execution or deportation to Germany, into a man who realises that, when faced with the choice between right and wrong, he ultimately has to take sides. And, when the time comes, he will do what his conscience will tell him to do, even though this will mean his own death.
Vittorio De Sica is great, as usual, in this dramatic role as well as in his comic ones. Non-Italians may find interesting the fact that Vittorio De Sica was himself an unrepentant gambler in real life as well, to the point that, if I'm not mistaken, his dead left his family saddled with debts. The film also gives a good idea of what life was like for ordinary Italians under the German occupation between 1943 and 1945. Many had to make difficult choices in a confused situation, and they reacted differently. Some took sides and risks, on both sides; others tried to survive. Some came to accept humiliating compromises in order to save their loved ones from death (consider the character of Borghesio, the old, retired lawyer who mortgages his house in order to gather the money that is needed in order to buy the German officer responsible for choosing the prisoners who are bound to be sent to Germany as forced labourers, which often meant death, or of Ms Fassio, the wife who ends up humiliating herself in a desperate and vain attempt to rescue his husband and is torn between her inner contempt for the Nazis and the urge to do everything possible to save his husband). Some others tried to profit from the situation. Some others made different choices in different moments, sometimes cynical parasites, sometimes heroes. However, everyone faced dilemmas, often about their very survival.
