Getting to see some more of Rapture is cool.
The story is absolutely fucking shit. If you want some sights and gameplay, then by all means, go for it. But if you enjoyed the story of Bioshock and Bioshock Infinite, avoid. The DLC strains to connect the two worlds, creating plotholes, making characters act out of character, changing motives, turning much of the backstory senseless so that, yes, it can feel connected. And in doing so reduce Elizabeth to a footnote of the original game.
Goddamn Burial at Sea part 2 was garbage. Between what he did to the continuity, characters, and his staff, Ken Levine can go fuck himself with a cheese grater. Wish I could get my $20 back, but he'd probably just swipe it from his employees' severance checks.
I'd get into it in more detail about the plotholes and stupid shit with spoiler tags, but I don't feel like raging right now. I will, however, post some images.