Setup, but done really nicely here.

I love the character interactions we get here, Brax and Romana, Leela and Romana, Romana and Romana...... Okay mostly I just love what we get of Romana here, but in my defence, Romana's really good.

Brax's interactions with Narvin here are also pretty nice, I like his confession of what he's doing with time travel, and then his, glee isn't the right word, but just how quick he is to suggest a mind wipe of Narvin after the events of the story.

Romana 1's appearance was an unexpected surprise, but it was great for the story. I love the backstory we get for Romana here, her childhood, Brax mentally manipulating her, the retconning her reason for regeneration in the main show. In another writer/actor's hands it could be a lazy excuse to retcon out a somewhat out of character moment for Romana from the show, but here it's elevated, adding a sense of intrigue about her origins, and setting up what I assume is the ongoing thread of this season.

Also a last note, I like the worldbuilding touch that the myth of Pandora is universal, that every world has some equivalent of it.