I recently finished up Mafia. Not too bad, it had a nice narrative and looked good, but as a game it wasn't great.
There are far too many cutscenes that take over from the player's control right in the middle of a mission, which is frustrating, and the missions themselves are short with very long narrative cutscenes. Fortunately, the voice acting is extremely good so watching is ok, but I found the lack of player involvement frustrating.
The game has, for it's style, a somewhat unique approach to acquiring cars and driving around. Police will react to your speeding or reckless driving, and you either have to stop and pay a fine (but there's no money tracking, so it doesn't matter) or evade them which can be tedious. While the realism is initially welcomed, it gets hugely frustrating after a while to be driving slowly when you're trying to get a mission done.
What is neat is that because the game takes place between 1932 and 1938, you see the cars on the road changing and developing. And the city environments are extremely well done, but you can't really get out and randomly explore (as you can in GTA). It looks nice but it's all very much on rails and your time in the city is tightly confined.
The missions have entirely too much try, fail, repeat built into them. On the one hand it's nice to have to approach things tactically (you can't rush in guns blazing) and you often have to scrounge for guns and ammo after you run out), but as the game progresses enemies just become ludicrously hard to kill.
I picked this up because I'd heard good things about the game (which I'd previously vaguely been aware of) upon the announcement of Mafia 2 coming out. It wasn't bad, I did actually finish it, but nothing I'd ever replay.