Never played Minerva's Den. I used gamefly on Bioshock 2 so the dlc wasn't around yet when I beat it.
I think the appeal of the original Bioshock is almost completely in the narrative. Actually playing the game isn't that fun outside of the story stuff and the immersion which is strong.
Bioshock 2 was a better playing game but the story was weaker and the immersion was less unique the second time around.
My favorite part of Bioshock 2 which I found poignant.
spoiler (click to show/hide)
http://www.youtube.com/watch?v=LwwHu8GxfCU