The game itself is awesome. Very atmospheric, quite long for a next gen release, very immersive and just tonnes of fun. It's the first game i've bought for my PC and thouroughly enjoyed in quite a while. Crysis was too "wow look at me...i'm shiney", Hellgate london was a waste of time and a huge letdown, unreal 3 was another let down and the same goes for alot of games recently. There is masses of fun to be had with plasmids (Genetic upgrades which give you various powers) and using them in combination with weapons which can be upgraded just increases that fun (think Painkiller). Freezing a Splicer and then smashing it to peices with a wrench takes a while to get old then you do it with the more difficult and annoying splicers and a rush of satisfaction goes through you as you kill a particulary annoying splicer that just wouldn't die. The story isn't the most original and fantastic thing you'll ever play through but it is still packed with dark humour and is voice acted quite well. There is tonnes to explore in each level and lots of upgrades to find/buy from hacking boosters to health upgrades.
Now, to the down side. Firstly, for this game to be worth buying for the PC you need to be able to play it on the full settings. I play it on an XP system specialy built for gamming and i have to stay at a resolution of 1024x768 and switch of "Force global illumination" to play it smoothly, i can't comment about running it on vista with full DX10 settings.
My spec is:
Intel core 2 Duo E6750 2.67ghz
Nvidia 8800GT OC 512mb edition
2gig OCZ Reaper 1066mhz ram
If you want to check if you can run it and how well you can run it before you buy it just google "PC requirements lab", install the plugin and it will test your PC and give you a detailed analysis of your system and tell if you can run it on High/low and what is stopping you from running it on high/low if you can't.
Secondly; If, in theory, you are lucky enough to be able to run this in all it's glory theres no garuntee you will actually be able to. There are a mass of flaws and bugs in the game even after a Patch/Update (v1.01) that will cause random crashes and the sound not to work. I personally have problems with the sound and did have an issue with the game crashing whilst it was saving at the end of loading the "Neptunes Bounty" level. I havn't managed to fix the sound but the loading bug was a problem with bioshock corrupting save's if you overwrite an old one. To fix it i made a new save just before i loaded the level, exited the game, loaded the save i had just created and then preceeded to the next level. Others are not so lucky, especially people running windows vista from what i have seen while trawling the net looking for bug fixes and answers. From the contact people have had with 2K games it looks like they have given up and are providing a shocking level of customer service.
As already mentioned, this game has some security which can cause some problems. The security is called "SecureRom" which is anti-piracy software which is well known for causing various problems and conflicts with software AND hardware.
If you are unsure about buying this game for the PC and you own an Xbox 360 i would suggest you go buy it for your 360.