As exciting as watching two people have a casual chit chat for an hour or two is, who out there doesn't wish that the scene in this episode where The Doctor first visits The Master could have gone on for at least the better part of an afternoon? As The Doctor later laments, they were almost "at school together" in a previous time. What tales they could tell of when they once were friends. Seems almost a tragedy that The Master lets the audience know that the game is up at the very end of that scene, laughing maniacally as he does while starting up an exercise regime on the rowing machine.
It's the fascinating relationship between The Doctor and The Master that almost completely offsets the rampant overuse of the character in Season 8. The Doctor/Daleks rivalry is completely black and white - we see how it starts, and we've seen (one assumes) every skirmish that the two enemies have had in the history of the show. There's no mystery there. Daleks hate Doctor, and vice versa. On the other hand, The Doctor never wants to see The Master destroyed, and, despite all his boasting and his cliffhanger-friendly antics, neither does The Master want to see his possible one-time friend die. It's a tantalizing prospect to want to know everything that went on between the two before we meet The Master formally in Terror of the Autons, but one that we are never allowed to see.
One thing that we are allowed to see is that utterly delightful scene where The Master whistles along to an episode of the children's show The Clangers before being interrupted by the completely humourless General Trenchard. Only Roger Delgado could allow The Master to have such a "human" scene while still retaining the villainous dignity of the character.