I've played a little of it. Not as good as MAfia. The cars could have been much better. The ability to build your story is better than Mafia. I haven't play that much of it, because personally I thought it was inferior to Mafia.
If I had designed this game, I would have combined the best bits of Mafia with the ability to be your own boss. You should be able to send out hit men, and sit back sometimes, and get reports. Other times you might want to have meetings.
They should make two games: one called Capone and one called Eliot Ness based on this kind of era (1930s) and use some of the above features.