I've played both InFamous 1 and 2. Both are awesome. It's a sandbox game with a bit of third person shooter-ism to it, except guns are substituted with superpowers. The story was great in both PS3 games and the alternate endings add replayability (you get the choice to be 'good' or 'bad').

From what I know of Second Son, the protagonist isn't Cole MacGrath, so I'm interested to see what powers are unveiled. The best parts of the InFamous games are unlocking a new power and proceeding to muck around with it.