The diaoogue audio is cut together from audio in the base game and from audio in Mass Effect 2.
There's also other smaller stuff like being able to invite her up to your cabin to hang out and cuddle and shit at any time if she's a locked-in romance. Her anti-Cerberus operations are also like a little mini game where you fund her missions and choose where she goes and when she comes back after a mission, you get a return on the investment and her War Asset value can increase or decrease depending on the level of success of the mission, how many other anti-Cerberus agents she recruits or die on a mission etc.
This also means that she gets a proper romance scene in Shepard's Captain's Quarters just before Priority: Cerebrus Headquarters like the base game squad mate romances. It let's Miranda be a squad mate (with EGM squad mates pack), and after Priority: Horizon, you can invite her to continue her anti-Cerberus operations aboard the Normandy.
