I played recently at Mafia 2 (thanks GWG on Xbox 360) and my opinion is far to be good.
Firstly, the open-world is just a joke, she are making for marketing purpose only. I think 2K wanted to have her own GTA, but I don't believe it's a developers will. The city is empty, dull, no activities, no cool things to do. The only interest of this open-world aim to improve the lifetime with round trip between a point A to point B.
Regarding the script, he is flat, the characters are caricatures of mafiosi. No cults scenes, and the end of game with the revelation of the murderer of our father is totally ridiculous!
The gameplay is annoying. The gunfights are boring, feeling with guns is very flat. And then, you want to talk about cops? They runs after you in all town just for a speeding ticket! It's "funny" the first 20 minutes, but after that is damned boring!!!!!
However, Mafia 2 is not totally bad. Some sequences are astouning. For example the part in prison, or the different weather (winter and summer). I would like to see the same things in GTA.
For Mafia 3, I hope 2K will abandonned the open-world for a linear game. I want they focus on script, the universe, characters and gameplay. 2k Czech doesn't have the means to reach a game like GTA, no doubt on it! They focus on the principle, a story on Mafiosi, with mature dialogues and a good gunfight system.
Thanks for reading me.