(SPOILER WARNING) Assuming you heard that there will be no Big Daddies in it. But if you heard that the game would be a prequel, possibly from the awesome and shockingly well-informed TR commentors, then that was right, actually. As for the Big Daddies, well, you are one. From Kotaku:
In fact, you’re the first of the lot, a so-called “renegade” Big
Daddy who’s on the hunt for a Little Sister of his own, according to a
tipster who has the new Game Informer magazine in hand. You’ll take out
rival Daddies with your huge hand-drill and plasmid powers, claiming
their wee sidekicks as your own. Similar to the first BioShock, you can choose to either harvest your Little Sister prize for ADAM or you can adopt her as your own.
That Little Sister comes in handy. She’ll harvest ADAM from corpses
strewn about Rapture, acting as a warning sign for when the Big
Sister–the lithe, lightning fast enemy who will hunt your character
throughout the game–has you in her sights. Based on her description, it
sounds like she’ll one hell of a fight.
From what we’ve heard, players will have access to all the things that made the Big Daddy such a menace in BioShock, with the character upgrades and options available in the first game expanded to keep things interesting.
I am 1000% down with this. I enjoyed the hell out of the first Bioshock, but I’m glad to know there’s going to be a real, genuine gameplay change for the sequel instead of more of the exact same. Plus, I would love to use that drill on some of those undersea bastards, rather than spend all my time shopping at vending machines.