I played BioShock to the end and enjoyed it.
BioShock 2 on the other hand, feels rather quite pointless, half of the time I end up asking myself why I am playing the game, why I am running from point A to point B on another useless quest. I eventually got tired of asking that question an decided to replay Mass Effect 2 again.
It looks the same as BioShock 2, the story almost feels the same. And the fact that you can play as a big daddy kind of sucks, due to the fact that you are just as weak as the first character in BioShock, which was human. The game is a HUGE disappointment in every respect.