Immerse yourself in the deep world of Rapture. BioShock is a fantastic and a very originally well crafted game.
Also, the dark and creepy atmosphere adds suspense to the game. The music makes its contribution on this section of the game pretty well too.
The only thing that I didn't like is how the story is explaind throughout the game. It's a little bit confusing because you have to grab "pieces" of radio conversations and dialogues to know everything, and sometimes they are well hidden in the game.
The characters are very originally well crafted and designed. The concept of the Little Sisters, Big Daddies and Splicers are excellent. Instead of hating them (because they are your enemies) you will love them. Trust me!!!
Anyway, this game is fantastic and, despite I have bought it 2 years after its release, I have totally enjoyed it.
Now I'll prepare to play BioShock 2.