What I'd like to focus on in this review are some of the design elements. I'll try to stay away from any major spoilers, but depending on how picky you are, one or two small things might slip - if you are concerned about this, stay away from this review until after you have played the game.
I'll divide this review into kudos and rants. Kudos describe aspects of the game that I like, and rants describe aspects I think could use improvement.
Style: The most outstanding aspect of BioShock for me has to be the overall presentation. The design of an underwater city with a retro theme is done just right, and the sound environment is nothing short of stunning - this is a game that demands to be listened to with the volume turned up. Little audio diaries with nice voice work fill in the back story as the game progresses, helping you experience life in this foreign environment.
Pacing: I prefer games with lots of variety - I like to keep getting exposed to new and interesting environments or game play elements, and I don't like getting hung up on overly complicated boss battles. BioShock provides a number of disturbing and interesting areas to explore - from power facilities, to research labs, to apartment buildings complete with bathrooms. For most battles in the game, you can die with almost no penalty, getting brought back to life in a convenient resurrection chamber. This lets you slowly whittle down any tough enemies even if you are low on resources. No doubt some people who prefer more challenging gameplay will dislike this feature, but it suits me fine. I want to see what happens next, not spend two hours trying to get the button press timings right to unlock the next area.
There are a few sub-features within BioShock - hacking machines to control them, or photographing enemies to research their weaknesses. In these cases, as you progress far enough in the game, the sub-features disappear right around the area where they might otherwise become boring. I think the hacking worked out about right for me, but I could have done without the last bit of completing my research. These items are optional, but I liked how they naturally faded away as a game element, instead of being forced on you to the end of the game.
Another clever trick involves the use of upgrades. There are effectively two different economic systems in the game - Cash and Adam. Cash can be used to buy ammunition and medical supplies, while Adam is only used to upgrade your character. I like this separation because there's no anxiety about having to save your money for character upgrades, or worrying about trade-offs between ammunition and upgrades. Similarly you have four separate areas of active genetic upgrades - these could have been combined into a single track, but the existing separation encourages players to explore the different areas of the game: Combat, Engineering, and Physical prowess.
The rants are fairly minor issues - by the time the game ended, though, I did come up with a few issues worth noting.
Money Cap: Limiting resources is one option to control game play and encourage exploration. For example, the different weapons have fixed ammunition limits. So when the Shotgun goes empty, you will tend to use a different weapon. If there were no caps, you might be inclined to stick with your favorite weapon. For the ammunition, this works ok. However, the money is arbitrarily stuck at $500 (especially arbitrary as the money uses four display digits, so it caps at "0500"). I suppose this is to prevent the game from becoming too easy, but it seems very artificial, and just annoyed me any time I hit that cap, as I hated leaving money lying around that I couldn't use. Another cap is on the number of parts you can collect to invent new items - the problem here is that the distribution seemed skewed somehow. I'd have tons of one item which I couldn't use without another item that was scarce. Then I couldn't pick up more of the abundant but unusable items - not a big deal, just a bit odd. Another minor nit (maybe I missed something) - when inventing items, you aren't shown how many you have in stock. So it's possible to invent items which you can't carry, wasting your supplies. Figuring out exactly how many more you need is a hassle, and pulls you out of the game.
Button Mappings: For the most part, the controls work fine. In two instances, they did not. The A button is used to both activate items, and to play audio recordings (by holding down the A button). So sometimes I would hold the A button to hear a diary, but instead an item would have popped into view and get used instead. Since some of the items have negative effects, or get consumed when you use them, this was annoying. Similarly the X button is used to both reload (which can consume your genetic resources), or to initiate hacking. While hacking security bots, the X action often toggles as things move around, and it's easy to get the wrong action to occur.
Dominant Strategies: This one's in the eye of the beholder more so than the others. A lot of the depth of the game lies in exploring the different genetic modifications. However, I didn't care as much about some of the options which seemed clearly inferior in terms of beating enemies than some of the core attacks. There was, to me, insufficient motivation to explore how all the different plasmids worked - I'd try them once or twice, and lose interest. This extends even to the later weapons, which I appreciated for variety, but didn't seem to have useful advantages over the early weapons.
User Interface: One very minor issue - at some points you can travel between areas using a public transportation system. Areas you haven't been to yet are left blank, as is the area you are currently in. This caused some confusion, as it wasn't apparent that's what it meant. It would be better to show the current area in gray, possible with some kind of "You Are Here" marker. This is supposed to be a public transportation system after all.
At the time of this review, there are 100 unreachable achievement points for BioShock. These were enabled about two weeks ago, which typically indicates upcoming DLC (downloadable content). Searching the web I found an interview with the game's creator, Ken Levine, discussing possibilities for DLC. Based on that, it sounds like the additions will focus on extra reasons to play the game a second or third time, rather than the usual standbys of new levels. I'm looking forward to seeing what they come up with, although I expect it will be more along the lines of some of the extra features which I didn't fully engage with.