You recruit people to join your mafia.. do mission..buy property, weapon and vehicle.. then you level up. Have fun!
Be ready to spam your Facebook wall and friends with all the actions you need assistance with. I find their game to aggressive for sending out requests, but I guess it works for them. I will not play it and I blocked the app so it wouldnt clutter my wall.
I can't really get into the RPG games. I need real movement and action. I need something happening on the screen. Zynga's other flash games like FarmVille and FrontierVille aren't so bad though. You should give them a try!