On the one hand, it kinda devolved into a generic open-world time-waster, where I and II were mostly story-based action-adventure games. Car handling, as someone else said also made the game what it is for a large part, driving a Model T felt like it was from that era. The low acceleration especially made car chases high impact, which I haven’t seen done in any other games. The story was actually about the Mafia, as in Italian-American organized crime, and I felt it got diluted by the change of atmosphere in III.

I don’t think III is a bad game, it’s just not a Mafia game. They could have sold it under a different name, and made a proper Mafia III.