A Superior Sequel
I enjoyed BioShock 2 more than BioShock. Yes, my enjoyment of the sequel was dependent on a familiarity with Rapture built by the original game. A familiarity that allowed an appreciation of the interesting ideological twists that occurred in Rapture 10-years after the events of the original game. Yet even more importantly, it's a familiarity that allows the overall plot of the sequel to have a more intimate and powerful impact.
Many BioShock and BioShock 2 reviewers comment on how well-realized Rapture is: it's a fictional place that is so atmospheric and immersive it feels like another character. This is so true that my original exploration of Rapture often diverted much of my attention away from BioShock's plot. The original game's plot dealt with heavy issues of identity, free-will, family, and revenge. Yet half the time I was more aware of where Jack was than what Jack was. It was a distraction exacerbated by a story that lost some momentum after the mid-game plot twist and ended with an anticlimactic boss fight.
The sequel doesn't have the same handicap. With Rapture a known quantity, it's more of a setting and less of a character, the central focus of BioShock 2 is entirely on the Big Daddy-Little Sister relationship. It's always been the relationship symbolic of Rapture. Unregulated individualism causing desperate fanaticism leading to the enslavement of adults and the exploitation of children. As Big Daddies and Little Sisters are manufactured, to the rest of Rapture their bond is entirely artificial. Yet, Big Daddy Delta's quest to be reunited with his Little Sister Eleanor becomes the only genuinely redeemable aspect of a city gone entirely mad: a father in search of his daughter. By the final act of BioShock 2, I was more emotionally invested in whether Delta would be reunited with Eleanor than I ever was if Jack made it out of the city in BioShock.
Aside from story, BioShock 2 gameplay mechanics are also improved. The ability to duel wield plasmids and weapons seems simple but it is as satisfying and radical to the gameplay as when Halo 2 allowed me to dual wield needlers. The simplifying of hacking removes a big frustration from the original game. Although remote hacking feels overpowered at times. Most of the weapons and plasmids from the original make a return in the sequel. 2K did remove the Chemical Thrower which always functionally overlapped with plasmids anyway. They swapped out the Crossbow from the original for a Harpoon-type gun that serves the same Sniper rifle-type function. The inclusion of a new Splicer variant to fights also mixes up the action.
I played the PC version. It performed well with no crashes. I don't consider the DRM and install restrictions a reason to lower my opinion of the game.
For those that enjoyed the original, I recommend you play the sequel. For those that haven't played the original, get both from Steam and enjoy the experience.