Also you get to go outside and in the ocean.
Game is just fun as hell. It's easily one of the best first person shooters I've ever played. I think it lacks the nuance and storytelling momentum of the first game, but that's about the only thing I find to be lacking about it.
If you go into Bioshock 2 wanting good gameplay and awesome atmosphere, you will come away more than satisfied with it. If you go into it wanting something as memorable or as striking as your first experience with the original, it may come up short, but I highly doubt you'll regret it.
It's got my favorite story moment from either of the games, too. You know what I'm talking about if you've played it. The pacing is also much better. Don't play both back to back, but Bioshock 2 is definitely worth playing.
Yeah. I think overall the first one had a more interesting story, but the sequel definitely had at least a couple of "okay I did not expect that" moments. And the great thing is that these moments are payoffs to details, not really the core narrative, but things you hear about as you're playing the game.