These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Alternative Character Interpretation: Andrew Ryan, a control freakout to commit suicide on his own terms... or a father trying to save his son? By the time he realizes Jack is his son and under mind control, he's basically confronted with his own flesh and blood turned into something worse than a "parasite" and turned against him. He could easily have killed Jack using his control phrase, but what does he do? He orders Jack to kill him, maybe in an attempt at forcing a Heroic Resolve to break the Mind Control. Too bad for him it didn't, though Jack does seem to take an awful time deliberating his swings.
Rosies, the first standard Big Daddy you face following the first one. Unlike the Bouncers, which don't have a ranged attack, their rivet guns and proximity mines are an absolute nightmare.
Houdini Splicers, who appear from thin air, hurl a barrage of fireballs, and disappear, giggling. Research makes their teleportation more obvious. Before that, better hope you spot them in time.
Spider Splicers, who like to crawl around on dark ceilings before attacking in a storm of thrown meathooks or gymnastic kung-fu. They're also a lot tougher than other Splicers, even with wrench upgrades, and shake off plasmids faster.
Disappointing Last Level: How some fans feel about the last levels of the game after the scene regarding Andrew Ryan's death and Atlas revealing himself to be Frank Fontaine. Nothing, aside from getting revenge, drives the storytelling through the hotel suites and Little Sister factory levels. As an added bonus, not only is there barely any new gameplay material at this point, the final boss battle is an absolute pushover.
Opinion is at least split for the hotel suites level; some enjoyed the Character Development for Dr. Tenenbaum seen throughout this portion of the game, and coming across the cause of Yi Suchong's death got a laugh out of A LOT of people.
Ear Worm: "In the garden we are growing, many changes will be flowing, if you wanna be a-ma-zing, see the flowers we are raising!"
Ensemble Darkhorse: Sander Cohen seems to be very popular among the fans, if fanart and the like is anything to go by. It may be in no small part to his memorable lines and being completely insane, even by Rapture's standards.
There's a unique quirk of the Lot 192 MacGuffin that you come across in Olympus Heights and Apollo Square — when you take the first dose of Lot 192, your plasmid structure will start randomly changing. You won't be able to control what plasmid you have equipped and you can't use Gatherer's Gardens or alter your plasmids at Gene Banks (tonics can still be changed to your likings), but every time your current plasmid randomly shifts, your entire EVE meter will be refilled. Every single time, until you receive the second dose of Lot 192. Not to mention that you can randomly gain access to plasmids you don't ordinarily possess, like Hypnotize Big Daddy 2 if you're on a harvester playthrough.
You can obtain many, many tonics that enhance the wrench's power, as well as one which when you're hit in a melee attack causes electricity to shoot out of you and paralyzes your attacker, and yet another which heals you whenever you deal damage with the wrench. Taking all of these together means that you can pretty much make the game a cakewalk by just running up to whatever is pissing you off and smacking it with the wrench — even the final boss is easily dispatched in this way.
The crossbow is a fairly powerful weapon yet the standard steel-tipped bolts cost almost half as much as the 00 bucks for the shotgun or frag grenades for the grenade launcher. There's also a slight chance that the bolts won't break upon impact and an upgrade that significantly reduces the likelihood of that ever happening (save for the trap bolts), meaning you re-use the bolts again after picking them off the Splicers or Big Daddies. Combine all this with the ability of lag canceling each shot fired by switching to your plasmid and you have a weapon that can drop Big Daddies in seconds, even on the hardest difficulty.
The Sonic Boom Plasmid. While its range is a bit short it hits everything on screen and instant kills most enemies in the game. The mooks who survive are often left critically injured and on the ground making them prime bait for the wrench. It also costs almost nothing to buy from a gatherer's garden due to being a DLC plasmid. Then there's the Sonic Boom 2 Plasmid which while more costly has greater range than the first one and will instant kill anything that isn't a boss, Big Daddy or a boss mook.
"Oh rise, Rapture, rise... We turn our hopes up to the skies..." Hilarious, but not foreshadowing, as Word of God claims they only came up with the "city in the sky" idea after BioShock's development ended.
To say nothing of the fact that that song was composed in-universe by Sander Cohen who Anna Culpepper would refer to as "Ryan's Songbird".
"Sea-Steading", the idea of building autonomous city-states in international waters to be free of political interference. Even better, the creator of The Seasteading Inititive - PayPal founder Peter Thiel - is a fan of Ayn Rand (and was directly inspired by Atlas Shrugged), and practically paraphrases Andrew Ryan when he said "There are quite a lot of people who think it's not possible. That's a good thing." He's chosen the impossible. He chose... Sea-Steading.
Hype Backlash: The overwhelming acclaim the game received from the mainstream gaming press has led to a few cases of "BioShock is overrated!!" outcries from some gamers and independent reviewers, not to mention those who feel that the game was recycled and/or watered down in comparison to System Shock 2, its spiritual ancestor.
Moral Event Horizon: If it wasn't already obvious, you know Suchong has crossed it when you find an audio diary in Rapture Central Control containing him testing Jack's mind control by forcing him to break a puppy's neck against his will — when Jack was a little kid, no less! There's also Suchong slapping a Little Sister whilst lashing out at her, but that audio diary has a happier ending.
For Andrew Ryan, when he kills a woman in cold blood with a steel pipe after he finds out their conceived child was sold by her, to Frank Fontaine, because she was in money trouble. If it wasn't for that, he would've been more of a Non-Action Big Bad, but the fact that the woman he murdered is the protagonists' mother, and he's the one who finds his mother's corpse, really makes this notorious.
It's a matter of opinion whether his Great Chain philosophy even had morals to begin with, given his stance against altruism and religion. Objectivists disagree, are delighted to see the propaganda and are saddened to see Galt's Gulch in such shambles.
Killing a Big Daddy for the first time leads to a scene of the Little Sister bursting into tears and desperately trying to get "Mr. Bubbles" back up. It's bad enough if you're trying to rescue her, but you're bound to feel even worse if you're planning on harvesting her.
The biggest one comes at Rapture Center Control. After Ryan shows you that Jack has been under mind-control the whole game, Jack kills him at his own request. Atlas then "asks" if Jack could insert the genetic key into the self destruct mechanism. The player may take notice that, during this scene, they have no goals, which would imply that Jack is free... But the doors are still locked. You are not only are being forced to carry out the actions of the person that you thought was an ally, but the game itself is actually forcing you to make this decision.
The area before you fight Fontaine, The Proving Grounds, has you having to protect the Little Sisters from waves of splicers. It's utterly painful to see one die, most especially when you've spent the entire game saving them all.
Special Effect Failure: If you spend some time looking out the windows, it becomes painfully obvious that not only the 2D background, if visible, is the same in every case (the large neon "Fleet Hall" sign is especially conspicuous), it's also extremely low-resolution and wraps around, which means that the "Fleet Hall" sign and the large skyscrapers appear on both sides when you can look both ways (like, for example, in the tunnels connecting the residential buildings near the end of the game). Compared to the gorgeous introduction sequence, it looks like a seriously half-assed job.
Tough Act to Follow: Was this to Bioshock 2, with many seeing it as a good game but still a pale imitation to its predecessor. Bioshock Infinite on the other hand, completely averted it, getting praise on the same level and many players finding themselves preferring it.
Uncanny Valley: Think that the Little Sisters look creepy and that turning them human will make them look better? Fat chance. Turns out that thanks to bad animations (including horrendous lip-syncing), plasticky skin textures and big glassy doe-eyes, they unintentionally look just as creepy after you rescue them, if not more so due to the fact that they're supposed to be cute little human kids as opposed to demonic Creepy Children.