ShackNews has screenshots and impressions of BioShock 2, you can check it out over here.
The demonstration began with Tenenbaum waking the player. The first illuminated sight was of the player's own reflection in a pool of water--a reflection of an enormous Big Daddy, the helmeted hulks from the first title.
Lead environment artist Hogarth de la Plante quickly explained that the player character in BioShock 2 is the prototype Big Daddy, the first behemoth ever created. As the game progresses, players will discover more about how the prototype came to be--and what its purpose is.