The game engine was arguably the most impressive thing about Crysis. The fact that it was released Nov 2007 and still really hasn't been unanimously surpassed speaks volumes.
As a shooter itself, it wasn't particularly overwhelming although the nanosuit play mechanics did allow for a great deal of diversity without being unbalanced.
But it seems that one of the most impressive aspects of the engine was the use of a persistent open world environment that enabled the player to effect something from a great distance, explore other areas and return up close to see that the effect was still unchanged.
What it was NOT, however, was the best in physics, ragdoll or otherwise. Destructible environments seemed largely restricted to sheet metal shacks and break away trees, less impressive than Dice's Frostbite engine. Ragdoll physics for KZ2 were far more dynamic and visceral.
And the character animations themselves were not what I'd consider to be among Crysis' greater strengths either.







