I pretty much avoided this one because it looked too much like Infamous, and I couldnt see that it would be that great (I wasnt that impressed with Infamous when I played the demo).
Infamous is good. It has more than its fair share of bugs, graphical errors, and some of the missions are repetitious and stupid, but it's still functional and addictive when you get right down to it. The powers are reasonably balanced unlike in Prototype where you're basically a god.
I do have some complaints about the story *cough*, and the building traversal could have been more fluid like in Assassin's Creed, but there's nothing in there time can't fix. And now that the engine's already been made, the sequel will definitely improve on everything.
