I love Halo, but System Shock 2 is one of my favorite games of all time. Despite that, I still had a blast with Bioshock. No, it wasn't as memorable as Shock 2, but it had its own unique flavor that I still appreciated. Even still, there are plenty of areas where Bioshock was quite superior to Shock 2 (mostly in terms of how everything was presented).
Sounds like the PS3 port is pretty crap, though. I always thought it looked a bit off in various screenshots. I suppose I'll confirm this for myself later on. I was never planning on buying it again, of course, but I was hoping the PS3 port would be decent.