How is Bioshock 2 compared to Bioshock 1?

Yes I know, I'm late on the whole Bioshock thing. Anyways, I've been interested in Bioschock Infinite but I decided to play Bioshock 1 at least before I get Infinite. I recently played the first Bioshock and loved it. So now I'm interested in getting Bioshock 2. However, I've read and heard mixed feelings towards the game. Some say its pretty much the same as the first, or simply not as great. So can anyone simply compare the two for me please? How scary is Bioshock 2 compared to the first, combat, story, plot twists, antagonists, etc. Appreciate the feedback :)