The original game was a phenomenon I really couldn't understand, and a big part of why I disliked Facebook gaming so much. So it pains me to say that Mafia Wars 2 actually looks like Zynga has invested a lot in its development. It takes the cartoon style of Farmville to make a kind of cutesy but bloody gangster world, and while it's pretty cheesy and stereotyped, the much improved graphics and animations at least give it the appearance of a game!
After a really quick look at it, it seems that the basic game mechanics are pretty similar to Zynga's other games. The improved presentation means you will get something nicer to look at, which is at least some compensation for the hopeless mouse-clicking addiction you'll find yourself in. It would be great to hear from Mafia Wars fans if this sequel lives up to their expectations!