So, this does it for the DLC excepting Genesis, which I'm not doing because it has exactly two unused lines: Femshep saying she hooked up with Ash, and MShep saying the same about Kaidan, with both lines being identical to the normal opposite-sex versions. But anyway, Arrival. Not a whole lot, in truth. The only bit I found particularly interesting was that there were two more human prisoners that got cut. There are still "ghosts" of them left in the game, if you hit just the right camera angle (image and discovery by Tony Knightcrawler):
It's interesting that there were other prisoners that got cut. It explains the Reaper on the wall. But I understand why it was cut. It gives away to Shepard that Kenson's people might not be all there, and have been exposed to the artifact.