IIRC from when I played it, Mafia concentrated a lot more on the story and wasn't as much of a sandbox experience that GTA is. You couldn't just go out and start a cop rampage, raid speakeasies, or steal cars and store them in your garage at will, for example. It wasn't about getting to the top, just about one guy trying to make it in the Mob.This looks great...what are the differences between this series and the GTA series??
It also had that damn race car mission. If you think the race missions in GTA suck, try Mafia's without the patch.
EDIT: Still had a lot of fun with the first game, though. I loved the whole 1930's vibe that they had going with it, the story was very good, and on the PC end, you've got mods. The sequel looks incredible, but 2009?!