You'll play wingman with Garrus, attend a memorial for Thane, or watch a romantic movie with Tali. You'll spend a long time running around the newly unlocked area of the Citadel, meeting friends for drinks or inviting them to stop by the apartment for a chat. Citadel takes place just before Shepard begins the final assault that ends the game, and so it seemed like the most logical place to insert such content. The lion's share of the DLC's content, nearly three hours worth, is a chance to bond with your crew members one last time. Rather, what we really came here to see comes next.
If you think things are over by the time the new foe is vanquished, you're wrong.