So I played Bioshock 2 first oddly enough. And I loved the combat, I loved the setting, the story was interesting and the ending to me was fairly decent. Oh and the moral choice system was straight up stupid. Maybe it's because I didn't have any knowledge of the first Bioshock so the story didn't seem odd, there was no Retcon for me. I just knew Rapture was an underwater city, there were Big Daddies and Little Sisters. The rest was introduced to me through the game so any knowledge of Rapture came to me through Bioshock 2. I found the game to be incredible and it's still one of my favorite games to this day.
I then went and tried to play through Bioshock and... well I'm still trying to get through it. I find Bioshock's combat to be fairly dull. I mostly just Wrench everything in the face til it's dead and it sort of becomes a chore. I just got passed the Fort Frolic, and when Sander sends the huge waves of Splicers at you I sort of just walked around bashing them in the face one by one moving from one to another. Became kinda boring. I find combat in Bioshock to be either incredibly unforgiving or incredibly easy with no real middle ground. In Bioshock 2 I actually felt the need to plan ahead, to be strategic, and to sometimes just go insane with power as I drill through as many guys as I can as fast as I can. Oh and the Big Sisters are terrifying.
In Bioshock 2 I felt like I had a real goal, something that I was working towards and I felt like the antagonist had a real reason to fight against me. In Bioshock I like that I'm exploring a dead city and all that, but I don't feel anything is of real importance. I just do what the guys on the talky box tell me to because.... they tell me to and if I don't then I don't get to go forward in the game. And the antagonist just comes off as an annoying cad who just wants to spite me for no real reason.