Looks epic. Like how they've managed to change it via making you a Big Daddy, while retaining the basics of what Bioshock was. Looks as good looking as ever too.
I saw this on Kotaku earlier, it looks orgasmic. I like where they are going with the Big Daddy thing, although I hated playing as a Big Daddy at the end of the first Bioshock. It was a bugger fighting Atlas moving that slow. Hopefully the enemies are slowed down to make up for the player's loss of speed. I also wonder if they are picking up from where Bioshock ended, or using a new story. Bioshock 1 ended pretty well, so I hope they start up a new story.
Looks excellent! Good to see these newer titles getting sequels cranked out fast. It looks like they have really enhanced the mechanics from the first game, pretty big fight that they showed, it leads me to believe that there will be lots of them. I hope they keep the scare factor in there though, I was honestly more scared by Bioshock than I was during Resident Evil 5 .
It appears as though you can use a sprint feature like the drill daddies in B1. As for the story, it takes place shortly after your cleansing of rapture in the first one. http://xbox360.ign.com/articles/963/963432p1.html