I had good memories of this story so was excited to see it get the animation treatment. It's a relatively straightforward morality tale, but it's delivered in a fun way with the Doctor being known already to this civilization and us initially only being able to guess at the conflict. The Doctor has a classic monologue that even giving up one life for progress is one life too many, an ethos that carries the show sixty years later. As for the animation, this seemed noticeably better than the previous wave of 2D animations, it seemed quite slick. Seriously, how cool is it that these episodes get this animated treatment? We're so spoiled.