Eidos Montreal's
Marce-Andre Dufort has been interviewed at Eurogamer to discuss the upcoming DLC,
The Missing Link:
Eurogamer: What exactly are we getting with this DLC?
Marce-Andre Dufort: You will get some technical improvements. We reworked the post-process, shaders, lighting and stuff like that, since we weren't really happy with what we had on the core game. We worked a lot on that. It is about five hours long, give or take.
More information.