I'm not going to comment on the gameplay elements or the storyline as I haven't played the game myself and don't have a Playstation 3 but from what I've seen of the morality system and what it gives to the game itself is rather disappointing and seems to be getting unfortunately common. Gaming companies that keep touting their amount of "choice" in their games that ultimately boils down to in the gamer's mind into "What makes me stronger?" or "What gets me the most stuff?" is bad design, along with the fact that it always seems to be two very, very, VERY obvious good/evil choices.
It seems to me the only people who can get the idea of "choice" correct in a game is Bioware, especially the Star Wars: KOTOR games. Though the answers can sometimes be a bit obvious, the consequences of your choices are more set in stone and have different results. Gameplay wise, if you chose to follow the Dark Side, you gained more money and equipment then a true Jedi would, at least in the short term. Though a Light Side Jedi would be spending more of his cash towards charity and sacrificing items instead of keeping them for himself, he'd gain better powers or better equipment down the line then the Sith so it was rather balanced whichever side you chose. Even Bioshock gave the idea that your choices had consequences to them if you needed that ADAM fix you JUST couldn't afford and all you needed was to kill one Little Sister. Even if you saved every other Little Sister, that one little slip into selfishness would result in the Bad Ending.
But Bioshock also screwed up in that you never really needed to kill any of the Little Sisters in the first place as their is no incentive to do so. You might not get as much ADAM if you save them but along they way you'll be given packages that gave you more ADAM and items then you could possible get if you were to play a child-killing ADAM fiend. And from my perspective, inFamous, Fable and even Spiderman: Web of Shadows makes the whole idea of choice in a game pointless if its so easy to go back and forth in being considered good or evil.
I guess all I'm saying is make the choices less obvious, the rewards for playing either side have its good and bad points and if you can't do that, just give us a linear story.
P.S. Also, would it hurt to have a game that shows that Evil doesn't equal ugly? Being evil should be enticing, something that looks like not such a bad idea. Because I'd rather not have my skin turn ash grey, get all crinkly and scared and have red, veiny eyes, thank you very much.
