It may have had some better gameplay implementations (the biggest one that jumps out to me is the improved camera/research system), but that wasn't nearly enough to overshadow the introduction to Rapture that the original gave us. The atmosphere in the original was unforgettable and the main reason why it will always be my favorite. Plus, it's difficult for me to suspend the disbelief that the sequel's villain, a character who they portray as Ryan's very vocal and public antithesis, was never once mentioned in the original.