My second play-through of BioShock has made me appreciate the game a lot more. When I rented it, I had 3 days to beat it, so I was in a rush to learn and complete the game. Not exactly the ideal way to immerse yourself in a game.
Second time through, I had all the time in the world to learn the nuances of combat, strategy with plasmids, and time to just explore the environment. This is the way the game should be played. It was stupid of me to form an opinion from just a 3-day rental.
The game truly is a very atmospheric experience. I actually took my time to notice little details in the game, and took my time learning the history of Rapture. The story is just...amazing, though it's essentially optional. You can get the gist of it by just a quick play-through, but to really understand the characters, their goals, their fates, you have to actively pursue that: collect all the audio diaries, listen to all the radio transmissions, and just observe the environment.
It's pretty amazing how the developers put a lot of thought into how the environment was set up. They didn't just throw some objects in a room randomly. They pretty much planned out each room to tell a story. Like you'll walk towards a room, and you'll have a ghostly vision of what had taken place in that room. Then what's left is the aftermath.
A good example is what happened to Dr. Suchong (SPOILERS, obviously!). You're goal is simply to get to Dr. Suchong's clinic and pick up an antidote to cure yourself of mind control. In his clinic, you see an audio diary. Your instinct is to just pick it up and leave. But you pick it up and listen to it, noticing how the diary is right next to a dead body. You hear Dr. Suchong talking about the bond between the Big Daddy and Little Sister. A Little Sister bothers Dr. Suchong so he hits her, and in reaction, you hear a Big Daddy drilling into Dr. Suchong. You look at the dead body, and you see that there's a huge drill sticking out of the guy's stomach. You come to the realization that this is Dr. Suchong. Now, this has no affect on your goal, but it's just a really neat optional story that you can discover. This kinda stuff happens a lot throughout the game.
The same sorta stuff occurs in Metroid Prime, but instead of audio diaries they're text logs and the graphical detail isn't really there to present a story as strong as BioShock can. But still, I love this stuff.
So I take it back. BioShock isn't a so-so game. It's AMAZING. Go play it.