This looks interesting, like many people I was disappointed with Bioshock 2, but this looks pretty awesome. I am surprised how many people though are dismissing this as Bioshock in the sky, the trailer does show what looks like different motivations in the city.
For example, Rapture was created to embody a Libertarian paradise, when there were no restrictions on what an individual could do or achieve. People could splice and modify their own bodies at will and were subject to almost no rules (initially). The protectors of the society's most important resource are the big daddies, who for the most part are docile unless their charge is in danger.
Columbia on the other hand look like an inversion of Rapture, the posters around the city constantly tell of some kind of Holy Duty citizens must attend to and the poster of Columbia rejecting a deformed looking baby suggests that Columbia accepts only what it sees a pure humans, so ideas such as plasmids and naturally developed super powers are persecuted and rejected. The woman who saves the man in the trailer is quickly grabbed by the big Daddy styled monster, which suggests that the role of a Big Daddy like creature has shifted from a docile protector to an aggressive hunter.
The two cities actually effectively represent the two mindsets of American thinking around those periods. Rapture represents our Libertarian ideas were consolidated around during the Cold War, fighting against our perceived enemies that would support Communism and Collectivism. Columbia seems to represent the America that was present during the turn of the century, an America which was obsessed with moral, nationalistic, racial and gender principals, which again you see in the trailer with the posters discussing Holy Duty, the multitude of American flags, the poster of the rejection of the deformed (and therefore inferior baby) and even to a lesser extent, the almost cliched, helpless looking woman who temporarily saves the falling man.
This is just my two cents, but I think that its safe to say that this city is going to be more than just Rapture with a face list.
