I got Bioshock when it came out but I played Two Worlds first and then stalled about 1/3 way in due to the mouse acceleration and lag. While it was fun exploring and soaking in the environment, quick movements (needed for combat) made me spin/aim past where I wanted to and I'd lose my orientation. The patch and bumping my RAM from 1.5GB to 2GB smoothed this out for the most part. The leftover occasional lag was expected based on my old system.
The developers did an excellent job of the story, environments and atmosphere of the game. A lot of heart and soul was put into this game. Nice unique environment, good AI, variety of weapons/mods and decent length for a SP game this day and age (Took me probably about 14hrs though I like to explore all the nooks and crannies and not just rush to the finish). There is the idiosyncrasy of the city's penchant for stocking vending machines with ammo and combat focused plasmids. Probably other weirdness if one thinks about the city of Rapture too much and lets real-world logic get in the way of gameplay.
Since your in an underwater city, all the maps where indoors. Still, the maps felt open and even if there was one goal end point there were times when you could take different hallways to get to the goal. Even when there was only 1 path it was acceptable based on the closed environment, unlike the forced paths of HL2's city maps. Lots of little details throughout each map made the atmosphere come alive. In a ways it reminds me of Fallout's retro-future 50's style, but in a decadent underwater city instead of a post apocalyptic world.
The AI did a good job using the maps to its advantage. The humanoid types would dodge and use obstacles for defense. They would retreat, use health stations, and pick up dropped weapons/ammo too. The lumbering big daddies were not too bad after a while. Since they left you alone for the most part, unless you were aggressive, it was easy to get the advantage. Though it was a good idea to make sure you had space to manuevor and backpedal to so that you did not get stuck in a corner.
Its definitely a good game and worthy of a replay. I would have liked it even more if it was an actual FPS-RPG hybrid like System Shock or Deus Ex. While you did gain new items/abilities,etc. as you progressed, since they could be switched out at almost anytime (Just find the gene machine) it was like the usual FPS progression of items. You were not forced to make permanent decisions about your characters advancement.
Maybe this streamlining makes a better game since you can experience more of the gameworld in one playthrough. Maybe its just my nostalgia that misses what the old FPS-RPG hybrids offered. I think I still prefer what the old ones offered (Having a character strong in some skills and weak in others or middle of the road in everything depending on what advancement decisions you made) as opposed to a jack of all trades good at everything. I'm probably biased due to growing up on complicated sims and RPGs that seem to be a drying breed these days.
Still, its a great FPS even though I wanted more of a FPS-RPG hybrid. Maybe Bioshock 2 will improve upon this. In the meantime, I plan on replaying System Shock 2 and Deus Ex to enjoy the taste of the hybrids I miss.