When Bioshock was released, it promised three things: a mixture of RPG and FPS elements, the ability for players to solve situations in a variety of different ways, and meaningful moral choices which influence the story.
They were probably getting confused and talking about Mass Effect, because Bioshock doesn't so much fail to deliver those promises as it does lock them in a cupboard for 14 years and beat them occasionally with a shovel. Nevertheless, it's still a hell of a game.
For those of you who've had your fingers in your ears for going on six months now, Bioshock tells the story of Rapture - an Ayn Rand-inspired objectivist dystopia located, of all places, at the bottom of the sea. The player takes the role of an interloper who is drawn into Rapture's madness when his plane crashes in the nearby ocean.
Admittedly underwater objectivist dystopias aren't exactly a concept that's been run into the ground, but philosophical speculation aside you'll find that the game plays like pretty much every other FPS since the dawn of time. You'll basically be running through a variety of corridors and large rooms, collecting power-ups, and pumping ammo into everything that moves.
The game's biggest gameplay weaknesses are where it strays from the normal FPS formula. For instance, you can "hack" most anything electrical in the game to make it work for you, including vending machines, security cameras, and killer attack robots. This basically involves playing an irritating version of Pipe Dream, where you're rerouting a device's internal plumbing (!) while nearby enemies patiently wait for news of your success or otherwise. It's pretty stupid and it badly breaks up the game pacing, especially as you're going to feel compelled by the nature of the game to hack most everything you see. Later you'll be purchasing expensive autohack tools just to avoid interacting with the silly timewaster.
The game also includes a mechanism where you can take photographs of enemies for "research" purposes - take enough photos of a given type of enemy and you'll get a (often totally unrelated) power-up. You have to put away your normal weapon to get out your camera, so you'll regularly be sitting there fiddling with the shutter while crazed mutants are bearing down on you with murderous intent. The interface is a little less awkward than the photographic bits of Dead Rising, but the minigame as a whole is correspondingly shallower and mostly just irritating.
As a result of the above two distractions, you're likely to take a lot of totally unnecessary damage from enemies, which will bring into sharp focus another of the game's flaws - the enemies aren't actually very scary. Even on the hardest setting most foes don't have a lot of grunt to them. Moreover, if you die, you'll be reconstituted at a nearby "Vita-Chamber" free of charge with a full health bar and all the kit you were carrying when you kicked the bucket. Nearby enemies retain damage you did to them, so you can just charge back out and pick up where you left off, ad nauseum. This at first seems like a progressive approach to making a game that players of all skills can enjoy, but in practice it does nearly terminal damage to your suspension of disbelief. It's no coincidence that the recently released patch for Bioshock includes an option allowing you to disable Vita-Chambers.
One of the game's most memorable features is its use of plasmids and tonics. Plasmids are special genetic enhancements which work like magic spells, allowing you to throw lightning or fire from your hands or use telekinesis or, for some reason, summon a swarm of bees. They sound great but the majority of them are either useless or redundant so you'll probably complete about 90% of the game using only 10% of the plasmids. For example, being able to freeze someone solid sounds great in principle, but the lightning power stuns enemies for about the same duration and is extra effective against machines, so there's really no good reason to ever pull out the freeze effect. That's all compounded by the fact that you can only equip a handful of these plasmids at once, so there's little incentive to experiment with new tactics.
You also get tonics, which are your standard passive power ups. Again, you can only equip a limited number but in practice the list of things you have equipped will be longer than what's on the sidelines, and as with the plasmids, there's a fairly high ratio of things you just won't get any benefit from.
Bioshock originally promised that you could solve situations in a number of ways. You could use overwhelming firepower, stealth, creative use of plasmids, hacked electrical appliances, or the nearby environment to overcome any particular situation. That's great, but in practice you'll actually just use all of the above at once, all the time. Except stealth, which, as with most every game ever, is boring, poorly implemented, and unhelpful.
You may have heard about the "moral choices" in Bioshock. This boils down to what you do about the Little Sisters. These are little girls, brainwashed and mutated to become ghoulish revenants who collect ADAM, the genetic lifeblood of Rapture. Each Little Sister is defended by a Big Daddy (the pressure-suit wearing monstrosities that appear on the game's promotional material) and after a reasonably tough fight you'll get the chance to "deal with" the Little Sister. You can "harvest" her, which kills her but gives you a huge dose of ADAM (which you can use later to buy plasmids and tonics), or you can "rescue her", which removes the genetic damage to her and leaves her alive, but gives you less ADAM.
It ultimately doesn't really matter which you choose. If you rescue Little Sisters, they'll occasionally give you presents of tonics and plasmids, which mostly offset the lost ADAM. The game plays out exactly the same way, and at the end of the game you get one of two brutally short and highly lame "endings" which depend on whether you rescued the Sisters or harvested them. In this regard YouTube, as always, is your friend.
The above criticisms aside, Bioshock is still an amazing game. The graphics are both artistically and technically excellent. Voice acting is generally outstanding, and the characters usually have something to say that's worth listening to. The world of Rapture is deeply atmospheric, and well realised through a large amount of backstory. Plus there's a lot of bonus points to be awarded just for trying to intelligently criticise Atlas Shrugged in the context of a first-person shooter. The core gameplay is well implemented, satisfying, and rarely repetitive, and the story is engaging, well told, and of a high quality all round.
It's worth mentioning that I've played both the PC and 360 versions of Bioshock and I have to say that if you have the choice you should probably go with the 360 one. On any but the highest end machines, PC performance is spotty, and on two separate systems I've seen it repeatedly crash at inconvenient times. By contrast, the 360 has absolutely no stability issues, loses little in the way of graphical fidelity, provides easy and intuitive control via the gamepad, and as a bonus you can earn Achievements while playing.
If you have any sort of liking for first-person shooters then Bioshock should be on your must-play list. It's almost certainly about to garner all sorts of Game of the Year awards and come out in some kind of cheap "platinum" edition so keep your eyes peeled because this is an experience you absolutely shouldn't miss.