I finished the campaign on the hardest setting a while back. The game was good but I wasn't blown away. I don't think it was really any improvement over the original. I really hated those big sisters.
I felt that it was pretty much the same game, minus a different story, and a few minor elements (such as the big sisters & dual wielding). The multiplayer wasn't worth it. And it was really short. I bought it one day, and a few days later, I was done.
I put it up on ebay shortly thereafter and got a nice chunk of change back.