2K demoed Mafia II to attendees at E3 this year and according to most, the game looks nice and has a bit of stealth to it that those who have played Uncharted or GTAIV should find familiar.
Apparently, you can stick to walls, hide behind objects and the like, but gunfire can damage and destroy your hiding place, according to Kotaku.
Driving was described as being a bit slow, but not as slow as in the first iteration, and the radio in the vehicles plays music specific to the time period.
The city is bigger, more realistic and the game features a checkpoint system so missions will not have to be replayed all over again should you fail.
Basically, it looks good so far. Loads more about it through the link.