I've played up to the beginning of the Arcadia section of the game, and for anyone that cares, here's some information/impressions:
-Research is still in the game, but it works in a very different way in comparison to SS2. Basically you get a "research camera" and take pictures of your enemies. As you take pictures, a progress bar fills up(the amount of the progress bar that is filled up depends on the quality of the pic). Once it fills up, you get various bonuses like extra damage against that enemy, special tonics, ability to harvest organs that heal you etc. If the game was more RPGish, I would've preferred the research system of SS2, but for a more action-oriented game like Bioshock, I think the new system is more ideal.
-From what I've seen, the only way you can get ADAM is through the little sisters. This means letting the big daddies and little sisters go about their business isn't really much of an option.
-Lots of audio logs.
-Non-linear level design with lots of optional rooms and areas to explore, and you are rewarded for exploring thoroughly with some pretty useful items like tonics and stuff.
-Hacking mini-game is still pretty lame. There are a couple of alternatives like hacking by paying money or using a disposable autohack tool. Also, there's no real advantage in not choosing to hack every single device you run into. In fact, you'd be foolish not to hack pretty much every single vending machine that you come across. Even when dealing with turrets, it's really just a lot simpler to zap and hack rather than try to destroy it. Ofcourse, the turrets, even when hacked, tend to annoy you a lot more than help you, especially those rocket launcher turrets which cause plenty of splash damange when it keeps on attacking enemies that are just a few inches away from you.
-All characters are going to be a jack-of-all-trades. You can't really focus on a specific style of play...well actually you can but there's really no logical reason to do so, you'll just be at a severe disadvantage if you don't make full use of your hacking skill, and all your plasmids and weapons. All characters can get all plasmids and all tonics, the supposed "customization" part is that you can only use a few plasmids/tonics at any given time(you have to go to a gene bank if you want to exchange your current plasmids). So, I suppose you get a slightly different experience depending on which plasmids you keep with you, but really it doesn't make much of a difference and doesn't seem like it's going to add a whole lot of replayability.
-I thought the plasmids themselves were quite good. Sure, in the end, they're all pretty much used to kill your enemies, directly or indirectly, but this is an action game after all. And they're still far more interesting than most magic powers you see in other games. You can do stuff like turn big daddies against enemies, create a decoy to distract enemies, melt ice with fire etc.
Overall, I still think it's a wonderful game though.
