Fuck all the whiny faggot haters in this thread. Bioshock 1 & 2 were equally fun and refreshing enough. I like the gameplay changes made for B2, they made plasmids more interesting to level up, and the weapon upgrade system added more features. They also simplified and made hacking more enjoyable.
As for the story, it may not have been as epic and had the big reveal plot twist as B1, but I thought it was intriguing to see the Big Daddy prototypes and origins of Big sisters. And the father / daughter relationship added the needed emotional attachment to the player character.
Granted multi-player feels like a tacked on pile of mediocrity, but I seriously doubt many people bought B2 for this purpose.