The Saboteur takes place in 1940's Paris, France during the Nazi invasion. In the game, you'll do such things as driving fast cars, blowing stuff up, and killing Nazis in various ways, with guns, dynamite, or cars, whatever you think, you can do in this game. You can even smoke cigarettes by standing still and clicking the left stick.
You play as Sean Devlin, an Irish auto mechanic who came to Germany to race the Saarbrucken. However, after getting cheated out of the win by a Nazi, you drive his car over a cliff as revenge. The Nazis take you and your brother, Jules. Your brother is killed, but you escape the facility and you set out for revenge on the Nazis, meeting a colorful cast and playing incredibly varied missions.
The Saboteur is based on the true story of William Grover-Williams, so there IS an educational value here. You also learn more about Paris and the Nazis throughout the mission if you keep your ears open. Sean is a hero, looking out for the good of France and trying to stop the war at the same time. He kills a lot of Nazis during the game, and he inspires the people of Paris to join the Resistance during the game, so Sean is a good role model.
There is language, if you're concerned by that thing. There are also topless women, but this can be changed by turning the nudity switch on the options menu to "off."
The game isn't any less appropriate or violent than any other game out there in this genre.
If you're looking for a fun game with a great story and good characters, The Saboteur is the game for you, if you can avoid some bad words here and there. I never understood why people think that words can be offensive.