Am I imaging things, or did Tom Baker age heavily between Destiny of the Daleks (1979) and this story (1981)?

The Master returns for the first time since The Deadly Assassin (1976). I must say that they improved his look, by letting the actor use his own eyes (rather than having those terrible fake eyes).

Not the most interesting story. A lot of time, in the first episode, is given to exposition for the premise of the Keeper and of Traken. It's legacy is the introduction of new companion Nyssa and the Anthony Ainley version of the Master (which existed for the remainder of the classic era).