As for pre-released footage looking better than the final versions, I see it happen often (regardless of platform). The latest that I can recall is Bioshock Infinite. If you look at the 2011 gameplay demo, the battles seemed to have a much grander scale (traversing large stretches of sky rail), and it made the world and characters seem far more reactive than what the final version delivered. It's probably a mix of the developer wanting to build hype with their games, along with the nature of development (cuts, redesigns, etc.).