I finally put in the hours to play this through, and wow. What a devastating critique of Randian Objectivism - but not quite a rebuttal. I enjoyed the story enough to turn the difficulty down to Easy so I wouldn't have to expend so much effort on the mechanics of staying alive - and this is the nature of Rapture in microcosm.
Firstly, the game. I enjoyed what appeared to be flashbacks to the Thief series. Enemies that move faster than you, ghosts, shadows, and security cameras which I'm sure must share actual code with those from Thief II. The combat experience is sort-of-neat, with a resource-management tradeoff in guns versus plasmids - swords versus magic in another context, or metal versus energy in yet another classic - but I fear I have grown too old to truly enjoy violence which is ultimately neutered by the environment being impervious to all your guns, rockets and pyrokinetic superpowers. You can blast a splicer into gory pieces, but the illusion comes crashing down when high explosives just bounce off windows. FPS gaming is about a decade overdue a truly destructible environment. Rapture has delicate glass walkways spanning underwater towers. I want to bring them crashing down with a rocket launcher and flood the hallway back to the last bulkhead!
But that's just me.
I think there is also an anti-drug subtext. ADAM destroys the citizens' minds to the point where they are concerned only with their own ability to get more ADAM. An addict is only interested in their own addiction; a self-centered life in the extreme, but if an addict's will is that he lives only to indulge in his drug, then is it not rational self-interest to pursue this lifestyle to whatever extremes he sees fit? Ryan's individualist philosophy agrees, and he can not bring himself to outlaw ADAM.
Going back to the main thrust of the plot, Andrew Ryan believed that society is driven by the will of great men. In this, he was right! He built an underwater city which thrived for many years - a success by all accounts. What he did not appreciate was that while society is driven by the will of great men, it is fueled by the toil of ordinary men. Fontaine said: "Somebody has to scrub the toilets."
It becomes apparent that the greatness of Rapture would not be possible without both the great will of Ryan and the hard labour of everybody else. To play the game is to learn this lesson yourself, as it is at once a beautiful, gripping work of art, and yet also a slightly tedious pseudo-RPG. While exploring gilded spectacles, you will have to stop frequently to search corpses for ammo, crates for spare parts, and yes, you will find the odd useful item in a broken cistern. To experience the joy of Rapture, you must at once be the hero protagonist, and the lavatory-scrubber.
Bioshock should have been a movie. Fallout 3 is a much better game.