Just got the platinum trophy for this game and I must say.. Absolutely fantastic.
I've put probably 3x as much time into Crysis campaign as I have into C3 single and multiplayer combined..
If you haven't played it yet, I highly suggest it. But divorce yourself from everything you know about c2 &c3 playstyle.. Except cloak, armor, energy.. Almost nothing else is the same.

Delta difficulty is one of the most challenging fps experiences In recent memory..
Very possibly my favorite fps campaign, ever. Especially stealth oriented fps