During the first games I've made my decision a "good" Big Daddy to be, so have all the Little Sisters saved instead harvested and got to see a corresponding to tears touching end. Especially the last 4-5 hours of play have me totally pulled and carried away in its spell. But even the hours before had an experience to pull through the decaying Rapture, always with too little shot in the magazine and a few health packs, always influenced by the incomparable atmosphere that produces the game, and always in fear of the well surprisingly emerging splicers ... well done and meets exactly my taste.
At the gameplay itself has not changed much, but I was the simultaneous use of plasmids (left hand) and weapons (right hand) quite handy. The new deal with the Little Sisters (whose original Big Daddy is first done, then you adopted the Little Sister and depending Sister twice ADAM reap where you have to protect the "harvesting process" before Splicers and Big Sisters, the Sister - then one may settle the Sister to a Vent and must again decide between saving and harvesting) I liked, here could be quite creative in eliminating opponents - I'm just saying Trap Rivets :-)
The story I was told again quite good, especially as mentioned the final phase was made class. The real star of the game for me is definitely the atmosphere: dark, incoming water, hissing pipes, metal creaking, whispering, screaming, screeching ... goosebumps.
My personal conclusion: If you liked the first part, which is also the second fallen. Too many changes can not be expected, but that's really not necessary. After Darksiders my second contender for Game of the Year, and it's just ... in February the year can be a really good gamblers for us :-)