In order to create the most immersive settings possible for Deus Ex: Human Revolution, the Eidos Montreal team had to build shining cities of the future from the ground up, and then they had to get them dirty.
It's one thing to create a futuristic city that's filled with clean lines and glowing lights. It's a much more difficult task to create such a city that still coveys the feeling of having been lived in. Eidos Montreal dirties up a city real good, from creating faux companies to plaster advertisements on every salable surface, to tossing about the sort of clutter you and I wouldn't bat an eyelash at in real life.
What they've wound up with is exactly the sort of Blade Runner-esque urban sprawl a guy could get lost in for hours. Looking forward to it.