One that I still can't decide if I love or hate is the Burial at Sea DLC for Bioshock Infinite.
On the one hand, it was cool seeing Rapture before its collapse, more of Infinite's excellent gameplay was welcome, and the additional weapons and powers were cool.
On the other,
killing off Elizabeth the way they did felt like such an unworthy end to one of gaming's greatest characters, I really didn't like the way they did that. Where Infinite saw her transform from a helpless victim to an awe-inspiring figure, Burial at Sea took all that away. It also kinda ruins the hauntingly ambiguous ending of Infinite. I feel like the series as a whole would've been better off without this addition, narratively speaking. In their attempt to tie up all the loose ends, they cut too many too short.
It was a downer, but I think it was mostly appropriate.
One of the big themes, if not the biggest theme of Bioshock, was child abuse. The Little Sisters, Jack, Elanor, and Elizabeth. In all of these cases the child is essentially sacrificed either to further an ideology or for straight up profit.