A lot of the geometry is simply and blocky in design, but I think that's largely for gameplay reasons. That's been an issue in a lot of modern games; angular large rock structures can look impressively detailed but a bit odd if they're meant to be played on. Same issue with animation and character control; people want animations to interact realistically and be weighty, but with such simple input devices, that almost always implies that a lot of actions the character does will be outside of the direct control of the gamepad.
Foliage is nuts; it's thick, beautifully rendered, and even the stuff off the gameplay area looks rich and interactive. A lot of stuff here is like that, the game world is very alive.
AI looks more interesting to fight than the stuff in the PS3 UC games, and at a glance seems to interact nicely with the new and more complex gameplay environments.
It looked like the flashlight was interacting nicely with deep water?
Would be really impressive if they actually bring this to something resembling 60fps.