Dr Who has always been prone to quick & flippant solutions but the current format of 45 minute episodes with a story line normally fitted into one episode, two for the seaon finale exacerbates the problem, there isn't time for a serious solution. This storyline needed three episodes, the first, as was, to create a mystery & give a hint of its solution as a cliff -hanger. The second to develop that hint of a threat into a realistic major threat with a cliff-hanger of doom. Followed by a finale in which the major threat is defeated in a logically consistant manner. Trying to make the second episode bigger on the inside makes the threat nonsensical, , turning UNIT into a bigger joke than usual, giving the cyber men unrealistic & unheard of attributes to develop it, and the solution is throwaway, apart from the credualty overstretching only two cybermen to keep emotions being The Doctors mates, the Mistress-Master simply, having spent all of human history collecting the dead, decides she didn't really mean it after all & hands the threat of doom over to the Doctor to with as he wishes.