Something for everyone
It seems necessary to begin with one of the game's alleged selling-points. Although some have made much of the moral ambiguity, in essence you make one decision: whether to be good or bad during your first play-through; in fact, you make it during your very first mission. After that, you are effectively compelled by game mechanics to toe the 'red' (bad) or 'blue' (good) line in accordance with your opening gambit; chances are you will then play through the game again, taking whichever route you didn't take the first time. This is not to downplay the attraction and game-play advantage of having the two routes through the game - the trophy system is clearly also designed to encourage a double play-through, and demands it of anyone aiming for platinum. But there is no point, no logic, and little reward in not playing consistently one way or the other, especially since several powers are dependent on increasing or maxing-out one karmic level or the other – in other words, there is no ambiguity as such, no sense of actually making difficult decisions (all is effectively pre-determined by your initial choice).
Barring fifteen karma-specific side-quests, the main missions and most side-quests are the same, and the game does as well as it can in incorporating these within a common narrative thread (e.g. by adapting some cut-scenes accordingly). On occasion it is forced - e.g. would the 'long since turned evil' and now infamous anti-hero really take time-out to retrieve medical supplies for a clinic? Replacing generic side-quests with more karma-specific quests would have helped here. The city does change, especially at the extreme end of either 'karmic' path – e.g. civilians will either take photographs or start throwing things at you; and the appearance and 'feel' of the city is very different in free-roam after completing the main story as 'hero' or 'infamous'. There is also a nice tactical difference to the two paths: the 'good' path requires far more precision, circumspection and care; the 'bad' path allows for more full-on frontal assault.
This is a 'sandbox' title, and the character movement is generally accomplished. Most buildings are designed to allow climbing and roaming without appearing artificially so; moments of frustration are few (e.g. making it to the top of a high wall only to find an insurmountable over-hang or gap). Ironically, the only downside to the intuitive fluidity of movement and semi-automated climbing is that the 'auto-grab' mechanic can sometimes make getting down again a slightly frustrating affair – it can take a dozen or more manual 'releases' to finally make it to the bottom of some structures as you catch every windowsill and ledge on the way; jump, and you might variously miss your target (e.g. a collectible half-way up a tower) or latch onto some other nearby structure. One blindingly obvious addition (for the sequel please!) would be a simple 'hold release button' option allowing a non-jump free-fall drop for as long as it is held. But otherwise the movement is fluid and well-balanced.
Enemy AI is adequate to purpose. Opponents generally come in two types: those that charge at you, and those that snipe at you. The latter do show some basic sense of cover (getting behind vehicles on the ground, retreating when you scope them on a rooftop), and there is some strategy in how you approach more entrenched positions (there is something satisfying in sneaking up the back of building and shock-waving a group off the roof before they know you are there).
Graphics are actually pretty impressive, given this is genuinely free-roaming in all directions. Is it any coincidence that this is a PS3 exclusive rather than a port or product of dual development? In this respect, Infamous really is massively superior to Prototype, its 'superhero sandbox' competitor. There is a consistency of rendering, detail and feel across the entire map. Some buildings are obviously based on recurrent templates, but this is hardly surprising. The draw distance is especially impressive, and the slightly grainy visual style, appropriate to the city environment, combines with a clever use of depth-of-vision blurring to generate real perspective without relying on a convenient low-lying 'fog' or on accepting mid-distance 'pop-up'. There is some reward in simply finding a very high vantage point and allowing the camera to swing panoramically around. The electricity effects are superb, thankfully, given their centrality to everything.
In short, this is pretty damn impressive for where we are in the PS3 life-cycle.