I remember going through GTA:VC and GTA:SA without the cheats and completing them. I then went back over the game sagain and did them with the cheats. As we all know the cheats had a knock-on effect with the gameplay of these two games, game saves were affected and so on.

I'd be hesitant to use cheats without completing the game first in case the same conflicts apply to the Godfather game, but I have to admit that when hiding behind a trash can with my health meter in the red and no ammo for my streetsweeper, cheats would be nice