I've been playing it since I got home from class this afternoon. It's OK, though I have some complaints:
It's a definite console port, with all the pros and cons that entails.
While the game tries to offer you "tactical options"--such as the direct assualt, a sneakier back alley, or a height advantage--at key points, the levels are generally short and uninspired. Enemies seem to swing back and forth between blind as a bat and eagle eyed, making it hard to get a real sense of which path really allow you to be sneaky. I've had enemies detect me from the street while I was crouching in stealth mode in the sewer below them. Levels are also generally small in scale and linear, offering very little real freedom of movement.
Default controls are a little awkward, with some actions downright inconvenient to pull off, such as the slide (W+shift+C), or melee attacks (V). In multiplayer, pressing 1 switches weapons, 2 switches fire modes, which causes me a ton of trouble. I ended up remapping the keys to the Half-Life standard and a few to my mouse as well.
Ammo isn't exactly scarce, but you can't carry much on you at a time, which can get annoying at times as you scramble looking for an ammo box or a dropped gun.
Suit energy can be a pain as well, as it seems to drain quite rapidly. You're forcing you to constantly take breaks from the combat while you wait for it to restore, which really messes with the flow of the game.
Suit abilities have also been trimmed down. Speed is completely gone, instead you drain energy while you run, despite the fact you don't move any faster then would in any other shooter, and for shorter lengths of time. Power has become context sensitive, and you can activate it by melee attacking larger objects like porta-potties or smaller cars, though neither move far enough when hit to actually be viable in combat. Essentially the only time you'll use it is during scripted "Press V to power kick the door down in order to continue" scenes.
Stealth is my favorite, but it drains your energy more quickly than the other abilities, forcing you to unstealth and wait 5-6 seconds for your battery to recharge. Again, screwing with the pace of the game.
Armour is uninteresting. You take less damage, but you move very slowly, which in turn causes you to take more damage.
Muiltiplayer is heavily investing in the console conventions. Matches are limited to 16 players total, are fast paced, chaotic affairs in small arenas, many of them based on single-player levels, though they are more open and interesting.
Crysis multiplayer takes it's cues from Modern Warfare 2's/Black Op's multiplayer, awarding points for kills, with bonuses for melee kills, headshots, and the like. Collect enough and you level up and gain access to new weapons, customizations, and abilities. If you like the multiplayer in those games, you'll likely enjoy it here.
In multiplayer, your level and unlocks make a huge difference, giving a great advantage to more prolific players. This wouldn't be so bad if there was some sort of level-matching, but there isn't. In most of my matches I have seen one or two higher-level players dominating, or have been matched with an entire set of upper-tier players, and have have struggled to get a single kill.
Eh, there's more, but this is long enough as it is.
TL;DR:
It's a console port. It's OK. If you like console ports or the multiplayer in games like Black Ops, you will like this.