Do we even need to talk about the game's graphics? You've no doubt been drooling over the screenshots and videos for months now. Yes, in addition to having a fantastic story and top-notch gameplay, BioShock is blessed with eye-achingly gorgeous visuals.
Much more impressive is what those graphics are used to create. Rapture is a masterpiece of design, a living and breathing game world that immerses you completely. Water pours from leaking ceilings. Schools of fish swim by the windows. Giant sequoia trees grow on the bottom of the ocean in sealed air tubes. A shimmering undersea volcano provides heat and light. The concept of a submerged society is bizarre, but BioShock sells it. Nails it.
The last question, then: Is it scary? Of course, but not necessarily in the way you're expecting it to be. Mutilated corpses line almost every hallway and screeching freaks occasionally jump out at you from the shadows, but heart-stopping, jump-out-of-your seat moments are actually few and far between. The permeating fear in BioShock is of a psychological variety.
Picture yourself entering an ordinary suburban living room, for instance, and discovering an entire family slumped dead around their flickering TV set. Some games would have the corpses pop up as soon as you got too close, but BioShock allows the quietly disturbing scene to speak for itself. The wife still rests her unmoving head on her deceased husband's shoulder. The children's legs dangle lifelessly, too short to reach the floor. Who are these people? How did they die? The answers your imagination provides are far more frightening than anything a lurching zombie could produce.