I feel like Orbis is kinda the Eighth Doctor's version of Trenzalore: the place he defends for hundreds of years and is willing to die for, and I really liked that we got to see Eight in a Time Of The Doctor-esque setting. There were some really heavy hitting moments, like when the Doctor tells Lucie that 'Sometimes people don't want to be saved, sometimes, it's time to die, you should respect that', an (in my opinion) incredibly profound line that really shows how committed he is to the planet. I enjoyed the other aspects of the story as a whole (although the ending was really depressing), and I'm hoping this leaves an impact on the Doctor-Companion dynamic over the rest of the series (shooting the Doctor probably won't do great things for the Doctor's friendship with Lucie I'd assume, and he's 600 years older).