Okay, so on the one hand, this can be accused very fairly of being padding padding padding. If you’re wanting your Doctor Who to be lean and mean and tightly plotted, I can see why this story maddens you. There’s literally not one minute of story here that’s essential to the plot of the Master going to Atlantis to get control of Kronos. If that’s the only reason that “The Time Monster” exists, then it could have been a three-parter. I understand that the low-budgeted series, throughout the Pertwee years, mainly adopted its format of two four-parters and three six-parters to make the best out of the resources available, but they honestly could have used three parts from this and one apiece from “The Mutants” and “The Sea Devils” and made an additional five-part adventure this year.
But I’m in the other camp. This is fun. The Doctor is being the stodgy old killjoy and the Master is having a ball. Benton gets turned into a baby, the TARDISes are materialized inside each other, and the Master uses his machine’s telepathic circuits to fiddle with the Doctor’s speech and have the words come out of his mouth backwards. If you’re bothered by the Brigadier turning into the Doctor’s straight man, only there to feed the star lines, he gets to stand in place for about the whole episode, frozen in time, so even he can’t annoy you. How could anybody not like this? It’s so fun.