Mafia is a clone of GTA III. In that aspect it's not very original. But what is original is the atmosphere. The cars handle like old cars. You're not in a V8 or a V12 with upgraded suspension. You're in an old heavy ford who needs all it's power just to climb the big hill of the city.
The story is a good one and the missions are diverse enough to keep interest. You really feel the city is alive not because of the number of people walking around but because you have all the cliché company around and you see them. Politics is there and you really feel that you're part of a Mafioso familly.
The game is not too difficult until the end where I had to look at a walkthrough.