First off, the game looks great. Any game set in New York better look and feel like New York; any game set in a New York getting blown to hell by Russians better feel just like that, and Freedom Fighters does. The various effects of gunfire and weapon explosions create an atmosphere of suspense and pressure. The interface is also nicely done. It's complete, functional, informative, but unobtrusive.
The sound is also very nice. The voice acting, while a bit comical and melodramatic at times, doesn't suck, and none of the Russian accents sound fake or forced, and on top of that, the weapon sounds are appropriate. You'll feel a sense of dread when you're walking down a quiet street and suddenly hear Russian voices screaming and gun fire erupting. The music ranges from so-so to inspired vocal renditions of Russian songs. Of course, when you start cleaning house, some more American style music appropriately begins to creep up.