Bioshock's one of my fav's because of the atmosphere, art design, voice acting, and attention to detail. I did, however, find some aspects extremely disappointing. Animations are meh, and the actual gunplay was no better than average... which is a pretty big con for a shooter.
All the mentions of Fallout 3 remind me that I liked that game for most of the same reasons I liked Bioshock. The voice acting wasn't as good, although this is partly due to Bethesda's brutal dialogue camera angles, hideous animations, and ugly not to mention boring character designs and facial graphics.
Maybe I'm just spoiled by Bioware's Mass Effect and Dragon Age though...