The plot is certainly a strong point.
The big plot twist is gorgeous, and wraps up a lot of the loose ends from the beginning of the game. Granted, it wasn't perfect because I didn't really *remember* the fake backstory, and it isn't given a lot of space. Also, I was a little disappointed there were not more details about the character's actual backstory. Of course, there are some big questions that you can ask from this point: where the hell did the character learn to shoot? How old is he, especially as he seems to be a physical adult?
Also, while I'm talking plot holes, consider the race to the sub in smuggler's hideout: who's in that sub, and why does Atlas waste so much time on them? Also, what the hell does Ryan think is going on, and why does he respond the way he does? I haven't played back through that section, but in retrospect it doesn't make sense.
The audio logs do a good job of revealing Rapture's descent into madness, and provide lots of little details and personalities that are relevant the only problem being how quiet they and the radio are compared to the action on screen: I frequently had to open the menu and read the text in order to understand what people were saying.
Also, I didn't find all of them. Which is frustrating, since I don't know where to find what is probably only a few remaining.
The first chapter is definitely the creepiest. After that, there were only occasional moments where the game reached the same heights, in part because after that you have too much of an arsenal.
As far as gameplay goes, it's an FPS, and I'm not a big fan of the genre. Sure, it was fine: nothing was a dealbreaker, but ultimately it wasn't the kind of game I enjoy the most and nothing can shake that.
Also, one thing I had trouble wrapping my head around was how easy the game was on a basic setting. The Vita-Chambers seriously warp the game, because their existence removes a number of obstacles. Fighting a big daddy or other obstacle can be difficult, until you realize there is no consequence for dying (unless you're playing on a high difficulty and trying for particular trophies). The Big Daddy's health doesn't even regenerate: if it's a close loss, you just walk right back and plug him, which I did at least once. That's really strange to realize, and to keep in mind.
As far as pet peeves go, I have to talk about the money. You are only allowed to carry $500 in the game, which is obnoxious. First of all, the counter includes a thousands digit, even though you can never get there. Second, after about the first chapter or two, I was running up against that upper boundary. I occasionally would spend it down several hundred dollars, but since every Big Daddy drops about 100 or so, and a lot of the later splicers and goodie boxes will yield 50 or more, that was very, very temporary. Given that that's the case, why have the limit? There's no logical reason for that, and I'd like to have cash as a way to "keep score", if nothing else.
Also, while I'm talking about random gripes, the water. I understand the designers wanted to have dripping, leaking water as part of Rapture's theme. And some of the leaks were fine. But there were some that were obnoxious violations of physical laws. The creators seem to understand some of the physics involved, and maybe I'm to blame for not being willing to suspend my disbelief, but sometimes things don't make sense. There was one in particular in Fort Frolic that caught my eye, where there is was a fist-sized hole in the glass window, and water was flowing in at a leisurely pace. In that circumstance, the window should have blown out, or at least the water should be coming in like it was shot from a high pressure hose.
But, all those gripes are minor. I liked the game, and I'm glad I played it. It was a nice change of pace from my regular fare.