How Good is Bioshock?

Many people have spent a lot of time over the past couple of weeks talking about how awesome Bioshock is (and it IS awesome), but nothing says more about how great it is than this: My wife does not play first-person shooters. They simply do not appeal to her at all. She got so engrossed in watching me play, however, that she decided to start playing. She has now completed the game once and has started it a second time, harvesting instead of rescuing this time. Now if that's not a testimonial, I don't know what is.