As an open world game, inFAMOUS (that is the official spelling) is a great package. It combines a variety of elements that, simply put, make the game fun to play, and overall a rewarding experience.
Firstly, one of the most prominent parts of the game is the combat. Although it may seem to be "Force Lightning spamming to git r done" it can actually get more deep and complex, especially because there are multiple powers to acquire along the way. On top of this, there is enough variety in the enemies that different strategies can keep things fresh and exciting. The game has a fluent, customizable, and fun combat system, and is even further rewarded by earning XP and getting upgrades for your powers.
Another thing that is important in the success of a game like this is the environment. It definitely doesn't disappoint and delivers great design, variety, and many different ways to get around. You can take high ground and stick to the rooftops, grind the rails, or stay by the streets and blast your way through town. Some people complain about the jumping mechanics, but I don't think it gets in the way of the action. Grabbing onto everything can seem a little magnetic, but just thinking of how frustrating it could be without that much to hold justifies the system.
And on top of all this excitement is a solid and involving story, lots of variety in gameplay, and a karma system that makes the game different on seperate playthroughs. All this amounts to inFAMOUS not just being a great game, but having replay value as you can have a completely different experience the 2nd time around going through the 40 chapters. All in all, inFAMOUS is a PS3 highlight and fantastic open world experience.