This is the Mass Effect 2 DLC you have been waiting for. Download it now.
One of my criticisms of the prior Mass Effect 2 DLC has been that it has no relation to the game's main story and feels like tacked on side quests. So out of the gate with this DLC, you have something special that feels like an integral part of the game. Moreover, if you played the first game, the relationship you had with Liara will impact your conversations with her as well. This alone makes this DLC stand head and shoulders above the rest.
And the DLC is not light on story either. Unlike the Overlord DLC, which had a great story but did not get to the heart of it until the very end of the content, the story here pulls you in right away and has several doses of development through the end to keep you engaged.
As for the gameplay, it's the same refined gameplay you experienced in the main game. However, there are also a few boss battles that mix things up and keep you on your toes. And there's a car chase sequence that actually feels more in place than the tedious vehicular platforming sequences in the Overlord or Firewalker DLC.
The Mass Effect 2 DLC is relevant to both the main story and your experiences in the first game and has the engaging storytelling that you expect from Bioware from start to finish. Why haven't you downloaded this already???