Chances are no, the graphics won't be much increased from before. I'm guessing they're going to be using the Crytek Engine 3 which is just a much more effecient version of the Crytek Engine 2 (the Crysis one). They said their next engine (4) will be a major graphical update. From the trailer it looks like we're getting some engine updates like weather. You can see the reflection of trees blowing in what could be a hurricane in the shards of glass floating around.
So think of this as a Snow Leopard to Leopard
But yea I can't wait. What really pulled me into Crysis was the story presentation, which is probably why I didn't like Warhead as much. Experiencing it all first time was kinda brilliant. And chances are it'll take place right where Crysis ends (where it shouldn't have ended, grah! cliffhangers

) but this time hopefully the boss fight isn't terrible.