Playing BioShock changes your perception on the darkness of humanity.. and the phrase "Would you kindly?"
Anywho, I got home and popped the disc in my X360 at around 2:00 PM today and I played it straight up until around 10:00 or so (Futurama and Family Guy came on so I had to pause for that). I played the demo before so the opening was familiar but different than what I was used to from that sneak-peek (THANK YOU!) and I got my real taste of the deteriorating, mutant-infested city of Rapture.
I knew about the physics engine; the whole deal about electrocuting enemies in water and starting oil slicks on fire. A few other things were overriding electronics or melting ice blocks, but I won't give out anymore spoilers of how that works.
But, I'll stop rambling on. We'll get down to business.
Graphics: Top-notch; that is what I call nex-gen graphics utilization.
Physics: Uses the Havok engine to it's fullest, but maybe just a little less than expected. (You cannot freeze water, furniture should be destructable.. especially it was lit ablaze naught but moment ago)
Gameplay: Almost seamless integration of RPG and FPS elements, however the storyline is a little hard to follow at times.
Bottom Line: If you can afford it, get it. If you can't, get a job. If you're not old enough but love a good M-rated game, ask your parents for Christmas. If none of those work, sneak out to a friend's house who has it. It's truly that amazing.