It was quite fun. Watching this story, I felt that the writer's imagination was still quite strong -- and I like to see how the story sets up the idea that our concept of "magic" is just a really advanced science. Delgado is both a despicable and engaging Master, and it is amazing to see how he and Pertwee have their intellectual fight across the narrative.

I would say that this is quite an interesting story. Maybe they could have waved the Time Lord's motivation to send the Doctor a little better -- like making him perform some missions to shorten his exile time --, but the way the Doctor argued with the Master in the final against using that "proto-Moment" was great.

It is intriguing on itself, but I felt that only the last two episodes became engaging -- in the end I was in suspense wondering if the Doctor was really going to run away or if he was just manipulating the Master...

Honestly, this story and season was quite amazing. I loved everything about this: from the intriguing concept of something deep into the Earth having such a dramatic effect on human beings to the Doctor's time in a Star Trek-style "mirror universe" -- which really helped us to show what was really at the stake on our main reality, and we can imagine how hard it must have been for the Doctor to have failed saving everyone on this other reality.