Initially I was wary of it, since like nobody from the original team was involved in its creation (or so I've heard), but then it came out and I heard it was "more of the same", which actually sounds like a good thing to me, and someone gave me a $25 Gamestop gift card for my birthday, so I picked it up. I will refrain from going off on a 30-page tirade about my experience at Gamestop. Suffice it to say I will make every effort to never set foot in a Gamestop again. Anyway, the game...
OMG this got really long. The short version is that Bioshock 2's gameplay is overall an improvement over the first game, but the story, presentation, pacing, and general "feel" of the game is nowhere near as good as the first game. Almost all of the horror and creepiness from the first game is gone, replaced by non-stop action. So, basically, this is Aliens to Bioshock 1's Alien. At first I was very put off by this, since I was expecting the same sort of moody horror that the first game had, but after a while I got used to it, but the negatives gradually outweighed the positive and I ended up being disappointed overall.
So, gameplay improvements! Hacking feels a whole lot more natural in this game; rather than stopping all of the action while you play Pipe Dream, you're instead just stopping a needle as it sweeps back and forth on a meter, a'la a golf game, while meanwhile the action is still going on around you, so if you're being attacked then you will continue to be attacked while you're trying to hack. This not only feels a lot more natural because it doesn't yank you out of the action like the hacking in the first game does, but the sort of "tuning in to the right frequency" feel of it makes more sense thematically than "rerouting mysterious liquid with little glass pipes". The whole "tuning" theme also lends itself well to the fact that you can now also get "hacking darts" which let you hack things from a distance. The camera is also much improved from the first game; whereas in Bioshock 1 you were taking pictures of enemies and getting points for framing and how active they were being, now the camera is a movie camera, and you start the camera running and then throw the widest variety of stuff at an enemy as you can before the camera stops recording, and are scored depending on how many different attacks you used, which is a lot cooler, more fun, and makes more sense. Also, there's unlimited film, which is very nice. Also also, there's actually a menu where you can track how much progress you've made researching each enemy type, which even tells you what upgrades you'll get for each milestone. That's something that the first game was sorely missing, as the only way to know when you'd completely researched an enemy type was that you'd get an achievement for it (on the first playthrough, that is. On subsequent playthroughs you'd just have to look for the tiny text that said "you've completed research on this subject" if you tried to take more pictures). Also nice is the fact that all of the upgrades have been divided into "plasmids" and "tonics", so you just have a whole bunch of slots to plug tonics into rather than having tonics split up into "physical tonics" and "mental tonics" and a couple other types I can't remember. Upgradeable plasmids are also a great feature, especially the security bullseye upgrade that lets you summon bots whenever you want, and the rage upgrade that lets you befriend enemies. Running around with two bots and a big daddy on your side is pretty cool. The crossbow has been replaced by a harpoon gun, which is more fitting thematically, and is also pretty ridiculously strong, especially when you get the rocket ammo for it.
Gameplay changes that aren't really improvements but are just kind of "different" include adopting little sisters and guarding them while they collect ADAM.
The biggest gameplay change that actually detracts from the game is the fact that with the drill (which is your starting weapon) you can literally go toe-to-toe with a big daddy, and once you get the "freezing drill" upgrade you can do so without even getting hurt at all. This completely removes all of the strategy from fighting big daddies, which was a pretty big feature in the first game. This is mitigated a little bit by the fact that your drill consumes fuel, so you can only go toe-to-toe with a couple of big daddies before you have to go buy more fuel from a circus of values machine. The total removal of big daddies as a threat is also mitigated somewhat by the introduction of three new enemy types who are as strong as big daddies but also very fast and mobile.
The story / presentation / feel / pace is pretty lacking across the board. The two good things I can say about it are that you actually meet a couple of characters face-to-face, and have the option of killing them or leaving them alone (which, of course, effects the ending, but they're just sort of cowering in front of you so you can't actually interact with them at all), and there are a few places where splicers are just doing their own thing and not attacking you, and you can choose to either attack them or just leave them alone, which I thought was kind of a nice touch. Oh, also, the "experimental teleportation tonic" was cute.
Presentation problems, though... oh so many problems. First is the fact that the story is just really dumb and shallow, with a very unclear and half-baked underlying philosophy, and it literally reduces the complex underlying philosophy of the first game to an amusement park ride. It feels like the writer did his research by skimming through half of the Wikipedia article on Randian Objectivism. The story is that you're a prototype big daddy who died before the civil war, and has been resurrected at a vita-chamber 10 years later, and you have to go rescue a teenage girl who used to be your specific little sister from her mom who's a psychiatrist and is now kind of in control of a small part of Rapture. That's it. No surprise twists, no questioning your own identity, just "go from point A to point B and rescue the princess". With a plot this simple, you'd think they could just explain it once and let it go, but every five fucking minutes you get a radio message from the psychiatrist mumbling some worn out new age drivel that has no bearing on anything, and then the next minute after that you get a psychic message from the little girl which just tells you to keep going, and then the next minute after THAT you get a message from Sinclair, this game's version of Atlas (who, in a surprise twist, does NOT turn out to be a bad guy but stays a good guy for the whole game until you have to kill him, making him one of the like three men with a southern accent in the history of American media who's not a bad guy) telling you to hurry up, and then the next minute after that you get ANOTHER message from Sinclair telling you again to hurry up, and reminding you where the next checkpoint is despite the fact that you're already moving toward it, AND there's a giant gold arrow at the top of the screen pointing toward it, AND the checkpoint itself is glowing gold and making windchime noises JUST IN CASE you'd forgotten what it was. Oh, and then after he's done talking the psychiatrist comes back on again and the cycle repeats. To spice things up, there are five different points in the game where YET ANOTHER person is ALSO constantly talking to you on the radio. This game NEVER fucking shuts up, but it also never has anything to say. I had to restart about half of the tape recorder messages in the game because halfway through listening to it someone would cut in to tell me about one-ness or remind me to reload my gun. Another problem is that the levels are linear; there's no going back to previous areas to get tape recorders, or plasmids, or little sisters you might've missed. Combined with the fact that you literally take a train from level to level, the game really feels like it's... well, you know what I mean. Despite being so linear, however, the pacing of this game feels terrible, whereas I loved the pacing of the first game. I'm not quite sure what the difference is, but this game really makes me want to pay close attention to pacing in games and try to quantize it, so I can figure out how to avoid all the pacing problems that this game has. Part of it might be the fact that, as I said before, you can just go toe-to-toe with big daddies and everything else in the game, so especially if you already have two bots and a big daddy or other major enemy on your side there's no reason to be cautious, so you can just plow on through wherever the gold arrow points you. By the time I got to the last level, I was so bored that I just ran through the whole climax in about 15 minutes, catching glimpses out of the corner of my eye of spooooky set pieces that must've taken someone a week to design, but which the pacing of the game made me NOT want to stop to look at.
Finally, there were several major bugs I ran into that surely should have been caught in playtesting. The worst two were a boss fight where the boss accidentally got locked outside of the bossfight room, so I couldn't fight him and thus couldn't get out of the room and had to restore a previous save (which, fortunately, wasn't so bad because I was playing with vita-chambers off so I was saving fairly frequently), and the second-to-the-last level where the game apparently lost track of how many little sisters had been spawned and failed to spawn the third little sister for the level, preventing me from getting all of the little sisters. I might be able to fix that by going back to a previous save and then saving again in a particular spot, but I was too annoyed by that glaring bug on top of getting bored of the game in general to try to fix it right then.
I also played a couple hours of the multiplayer, which had a neat intro, but was pretty dumb once I actually got into it (the fact that I was waiting in the lobby for about 10 minutes before enough people actually showed up to start a match pretty much says it all).
So... overall, there are a few neat improvements that could have made the first game more fun (the changes to hacking and the camera, and meeting some characters face-to-face), there are a few things that are kind of fun but which I think hinder the game's mood and pacing (summoning bots and recruiting enemies), and everything else kind of sucks.