The obvious thing to talk about when discussing the PC version of Crysis 2 is the visuals. The first one was, and perhaps still is, the benchmark for graphical performance, always the one you'd pick to show a friend “hey, look what my machine can do”. The second game won't be in this situation as, while it does look very pretty, it doesn't wow us like its predecessor did.
It's because of the more confined nature of the play. On the console version, the review of which you can read HERE, it's not so much of an issue. You do have freedom, enough to make you feel like you've got more than one option on how to get from A to B.
That doesn't change between the versions, but what it does do is make the visuals less special. Cities and corridors are fine, but there's nothing like the contrast you got between expansive jungles, alien structures and frozen wastes.
The alien bits don't really look too different to the urban scenes before them in Crysis 2. Yes, they're alien, yes, they're not of human design, but no, the diversity that made Crysis so delicious visually is no longer there.
However, all this does mean that any PC worth its salt will be able to run it very well. Never will you hear people say “Bloody hell, Crysis 2 ran like a dog on mine” like they used to with the first. That's got to be a good thing, but there's a part of your correspondent that does yearn for Crytek to have continued breaking visual boundaries. It's been a long time since the goalposts were moved, after all.
But what differences are there from a gameplay point of view? First of all, it's definitely a smoother, easier experience when transferred back to the mouse and keys. No amount of control shaping will make it easier to sprint with a press-in of a left stick rather than just using the pinky to hold Left Shift. It's also easier to just interact with the scenery, to plan more elaborate strategies and so on. Even though the move over to pad use has been handled excellently, it's clear where the game's roots are.
Therefore, it's much easier to get things done, which is actually slightly detrimental to the overall experience. It's easier to sneak, it's easier to kill, it's easier to outsmart your opponents – although the AI does remain as erratic as it is on the consoles, spotting you while you're invisible too often and also getting stuck clipping the scenery.
Generally, though, things are more similar than you might think. It's only really visually that things are markedly better on the PC, as even the console controls do a decent job in comparison (helped by auto-aim of course). It's perhaps a sign of how the game has been compromised for release on the consoles that there's not too much to really contrast and compare. Certainly, you'll only really be getting a better visual experience if you opt for the PC one.
That leaves the multiplayer left to compare. Well, the PC one has Gamespy as its engine, so naturally it's a horrible experience, at least initially. The log-in system locked thousands of players out from the word go, so to be honest there's not much point discussing it right now. There's also the cross-platform problem of a strange strict NAT issue that also afflicted Dead Space 2, although this is a strange one on the PC, because using dedicated servers as the game does, you'd think there'd be no issue with NATs or any of that cobblers.
Having said all that, it's a reasonably fun experience. There are quite a few maps to be getting on with and the action verges on the right side of frantic. Good players will naturally dominate, but there seems to be a place for everyone, even if getting stuck in isn't always your game. Kills aren't that hard to come by and it's certainly a more accurate, less frustrating experience than it was when played with the PS3 pad. Of most interest is the Assault mode, where players only have one life, just like in Counter-Strike.
So Crysis 2 on the PC isn't really a great deal better than its 360 or PS3 counterpart. It looks better and the controls are smoother (but not by a huge degree). There's no fault in the console version that's corrected in the PC one, and vice versa. They're essentially the same product, so just buy whichever one you feel most comfortable with. Really is that simple.
Oh, one more thing. I can forgive there not being a prone on the console version, but not having one on the PC is utterly unforgivable. It was there in the last game, it was there in the game before that. Even COD has it. So to be detected because I can't go to ground behind a low wall? Slap yourselves silly, Crytek. Please, do.