I know from a gameplay standpoint this is entirely irrelevant, but looking at the Master Chief on the video I noticed how battle-scarred he looks. I think it would be a nice feature to start you off all shiny and new (or battle-scarred depending on where the story picks up) and have you get more beat up as the game progresses. That video is the first one I've seen where he actually looks like he's been through a battle. I also liked how he actually has holster of some sort for his sidearm (or may he uses velcro to stick it to his leg).