After playing through the first third of inFamous (in one sitting mind you, which says something in itself) these are my initial thoughts.
Honestly, I'm having a blast. Playing inFamous hearkens back to my days with City of Heroes in that playing as Cole makes you feel really powerful. Not like, say, World of Warcraft where your character is certainly strong and well able to make his way among the many threats in the world; Cole truly gives the impression of playing a god among mortals without crossing the line of being too easy. When pulled off correctly this trick makes any game loads of fun.
This is partly managed through extreme freedom of movement, initially through Cole's 'extreme urban running' skills at climbing and jumping off anything and everything in a quick and intuitive manner and eventually augmented through superpowers. The rest of the effect comes from the powers themselves which come in an inpressively wide variety and are easy and fun to use.
As a standard GTA style 'find a mission on the map, then do it' game, inFamous is susceptible to one of that genre's biggest problems: stale filler. Most of these types of games use optional side quests to fill time between the main ones and to allow for some grinding, but usually offer only a slim variety of these missions that get old very quickly. Thankfully, inFamous overcomes this problem with a remarkable range of side missions, though of course some repetition is still present. My favorite 'love to hate' mission type is the 'building under surveilance' mission, in which Cole must clamber over all surfaces of a building disabling equipment that has been placed there. It sounds like it should be easy, but in reality its quite time consuming and more than a bit annoying. Most of the rest of the missions are a joy though, so its hard to complain.
Graphically speaking the game is on par with many current titles, though unfortunately that also means the standard 'everything is gray or brown' palette. The animation is unfortunately very... for lack of a better word, 'fake.' I realize that not every game can have the benefits of motion capture, but there are times when its certainly obvious that it would have helped. It takes a little while to adjust to the animation's eccentricities, but its certainly not a huge problem. Sound effects and music are solid. Unfortunately I have had a single hard lock, but so far I'm willing to call that a fluke.
All in all, inFamous is definitely shaping up to be a great experience. You'll get the full review when it's done!