In Mafia, you play a lowly taxi driver who slowly moves up through the ranks of the local mob. It's a blend of Vice City with 30s era Chicago.
The maps are huge, detailed, and you can go down every back alley and around every corner. The downside to all of this is that the load times to move from area to area are simply AMAZINGLY long. I don't think I've played a game in years that has had such tedious load times. This is DEFINITELY a game that you play with a glass of wine (Chianti, of course) and plate of cheese in front of you, so you can snack and drink while you wait. It's a lesson in patience.
The graphics are quite nice, although not stellar. The cars in particular are a bit "shiny" most of the time and objects really appear to have painted-on skins rather than having textures. Still, you quickly learn to adapt to the look of the game and get drawn in by the plot.
The plot is where MAFIA shines. Other similar games have plots that often feel very contrived. You're being dragged along into missions just to achieve a cool stunt or go through a series of obstacles. In Mafia, you really get to understand the main character, his choices, his dilemmas. He doesn't always do what he's told. He's not an angel, but he tries to stay true to what he believes in. The maps' being large helps with the feeling that you are a real person making real decisions. There isn't any "Go directly left then go 2 steps forward" - you can take whatever route you want and if you take the wrong one, you have to figure out how to get yourself out of it.
This also makes replayability fun, because there are 80 different ways to handle each situation and you never know which one might be the most ideal.
There are a good collection of era-appropriate weapons (tommy guns, sawed off shotguns, etc) and a large number of cars for you to learn how to break into. The starting ones are, as in any game, the typical low-milage, low-speed clunkers. As you learn more about cars, you get your hands on better and better models for your garage.
The AI is reasonably good. If you're perched in a window, the enemy will figure out how to get behind you and shoot you from there. They will cover each other while approaching you. We did hit a few glitches where you aimed directly at someone from point blank range and the system jumped so it "missed". There were a few clipping issues too with the graphics, but that happens in just about any game.
Overall, the game is reasonably long, and can easily take a few weeks to play through if you go for quality over race-though-and-miss-everything. The free roam mode helps keep the game interesting for even longer. This is a game that is fun to blast away in, but also gives you things to think about and characters to relate to.
Buy Mafia from Amazon.com