The world of Rapture seems to take its time drawing me in. With the first BioShock it took quite a while for me to click with the game and by time I did, it was almost over. As the sequel was announced and the release date came inevitably closer my interest was not terribly high but as soon as release week came I tripped over myself purchasing the Steam PC version (I played BioShock on the 360). I sort of messed around with it for a few hours and then chipped away at the game seemingly in 30 minute blocks for the next couple of months until last week when I realized I was about half way through the story. Being close to the end is always a big motivator for me to actually finish a game, something I don't always get to do.  By the time BioShock 2 was over I was once again completely immersed in everything Rapture.
 
Returning to the world of Rapture doesn't have the same effect as being introduced to it. The sense of wonder and discovery that you experience in the first game is completely gone and you're essentially thrust right back in to the action. Everything feels familiar and certain improvements are very welcome (quick switching plasmids, firing weapons and plasmids in tandem...) as you get used to life as a early Big Daddy prototype. Throughout the game you learn about your own past and the connections to the present. Little Sisters still wander around with their Big Daddy escorts collecting Adam but now you can be their protector or savior. The gatherings got a little old after a while but were required to upgrade your abilities and powers. Big Sisters prove to be a formidable foe with their quick movements and skin that's as tough as a Big Daddy.
 
By time the story is in its third act it really picks up steam and climaxes a bit better than the first game (had the first game ended with your murder of Ryan I wouldn't be saying this). The twists and turns it takes are not terribly surprising but well done and believable. I'm not the biggest fan of game narratives, but this one is fairly well done.