First off, one thing I'd like to point out is that it definitely feels like it was simply ported over from the console demos, but that's fine considering it's only a demo.
Second off, regardless of the first statement, it's fun as hell. I already had it pre-ordered before the demo released (This morning at 12:00am), and I'm really glad the demo gave me some fun. I'd have been upset if it turned out to be horrible.
I've been playing it most of the morning, getting more and more used to how it works. So far my tactics include moderately going in and out of stealth to keep myself hidden, taking my time to aim, then switching into defense mode and lighting my target up. Pro tip, go out of stealth before firing. If you fire in stealth, it gives you this obnoxious flash that distorts your view, and drops your energy straight to 0. I choose to switch into defense just in case the enemy shoots back, that way I can take a few shots.
You're probably wondering where you can get the demo, and you can right here - http://www.ea.com/crysis-2
Caution, this game is VERY graphic heavy. You DO need a good computer to run it decently. In case you don't know, Crysis is the game people try to run to see how good their computer is for gaming. It's known for having the best/most intense graphics of any PC game. I'm surprised that I ran it so well, even on Livestream.
Speaking of which I just got done with a benchmarking test using Livestream and Crysis 2. I turned the graphics down to "Gamer" mode, and my resolution to 1600x900. I ended up running 60 FPS, even with Livestream. Couldn't even tell I had it running! That kinda made me happy. Expect a ton of live footage soon.
Hit me up in game for the demo if you wanna play. My username is GoldenTot!