BioShock is a great game, but it relies too much on System Shock 2's story and gameplay.
In BioShock you assume the role of Jack, just Jack, from God to Kane to Jack- wait, wrong game. Uh, anyway after a very brief monologue (which happens to be the only time in the game "Jack" says a word) the plane he is on crashes conveniently right next to a lighthouse. Inside of the lighthouse Jack finds a bathysphere that takes him down to Rapture, an underwater "utopia" that has been thrown into chaos, and your only lifeline is a mysterious Irishman named Atlas.
BioShock is praised for its story and atmosphere. I will agree that BioShock has a great atmosphere, the underwater city concept is very original compared to other RPGs and shooters out on the market and the game features some very interesting locales, events, and characters that only help improve the immersion. Unfortunately, while the atmosphere is superb, the story left me with a sense of Deja Vu. Why? Because it was System Shock 2's story with a new skin. I can't say much without spoiling the story for those who have yet to play it, but if you've played System Shock 2 all the way through then you'll be very disappointed with BioShock's rehash of the plot. BioShock does contain a little bit of philosophy in its narrative, but it's mostly an anarchist theme, and doesn't have a strong presence so gamers who have played Planescape: Torment will likely be underwhelmed by what is there.
BioShock does contain an interesting story element not found in any shape or form in System Shock 2, the Little Sisters. The Little Sisters are little girls who are possessed by a slug and wander around rapture gathering Adam from dead splicers. Essentially you're supposed to either rescue all of them (the good path), or harvest their adam and kill them (the evil path). To do either you first have to eliminate their guardian Big Daddies. This is supposed to add some emotion to BioShock's dreary atmosphere, and it does to a degree, but some players will likely find the "kill the big daddy and rescue\harvest the little sister" side quest to get stale after a little while since you have to do it so much.
BioShock, despite being labeled as a First Person Shooter\RPG is dumbed down so much when compared to System Shock 2 that you might as well label it as just a FPS. Essentially it's a run and gun game where you can also use a "magic" system referred to as Plasmids by altering your genes, and to do this you need Adam. There are also certain tonics you can get that give you some bonuses such as improved wrench damage, and tougher skin, but there is no Strength, Agility, and other such base stats to be found in BioShock which is disappointing.
One big issue I have with the gameplay is the lack of variety. Every enemy in the game is either a Big Daddy, or a variant of a Splicer. Where are those creatures from BioShock's initial screenshots? Heck, where are the interesting enemies period? Fighting splicer after splicer gets old after a while, and the only time you can mix it up is if you encounter a Big Daddy protecting a Little Sister. System Shock 2 had a wide variety of unique opponents, so BioShock's lack of this is a major letdown. Hacking returns in BioShock, but it's a fairly tedious mini-game and I usually didn't bother hacking unless I had an auto-hack tool. Destroying security cameras and turrets seemed more efficient since you have generally killed all of the enemies in the area by the time you actually had the option of destroying\hacking said devices.
Visually BioShock is nice to look at since it uses the third generation Unreal engine. The hyped water effects are very good even without DirectX 10, and the textures and enemies are finely detailed. The audio is pretty exceptional as well, superb voice acting is present throughout the entire game and the environments have some very impressive background effects. The music in BioShock is a combination of an atmospheric score, and licensed American music from the 40s.
BioShock is a great game, but it plays a lot like a dumbed down System Shock 2, and the story is far too familiar for my liking. Still, if you're looking to get immersed in a unique setting then BioShock is a good choice, and despite the unoriginal plot it's still entertaining to follow even if you've played System Shock 2 through umpteen times.