I didn't really like episode 2, but I think that this DLC will really depend on how much love you had for the first Bioshock. It did some really great things, but I just wasn't feeling it like I did episode 1.
I thought the stealth sections were broken, even without the peeping tom vigor. The AI was pretty dumb, and you can pop in and out of the vent systems and murder everyone within a large radius. Maybe its just me being spoiled by actual stealth games (MGS), but I was not enjoying the gameplay at all. I will say though, Irrational did a fantastic job of making me really afraid of messing with the big daddy. There were some other nitpicky issues but whatever, I didn't really come to this DLC for the gameplay.
Storywise, I didn't see where it was going but was really disappointed on the payoff of what the ace in the hole was (Even Elizabeth kinda was like "This is it?" when she finds it). I also have a really hard time believing Elizabeth could not figure out a better way of saving Sally, even with the limitation of constants and variables. That and the fact that Elizabeth fit in too well with the lead up to Bioshock 1 bums me out. The Daisy stuff was disappointing, but not a deal breaker. I also really didn't like Atlas being such an important part of the DLC, since his arc in Bioshock 1 was the thing that made me stop playing after the twist. There's probably an argument on how episode 2 nullifies the moral choice in Bioshock 1 (a game all about choice and the lack of it), but I'm not gonna make it since its just getting nitpicky on just thematic stuff.
Episode 2 was well made and I thought the other stuff like visual and audio direction were pretty good.Heck even the scenes taken in isolation were pretty good. I just wasn't feeling the gameplay or the story.