The Key to Time series was a mixed bag, some great ones like The Ribos Operation and some rubbish ones like The Power of Kroll, and The Armageddon Factor falls right in the middle being a story full of merits and faults that level out perfectly.
This six-part finale revolves around the planet Atrios which is at war with it's twin planet Zeos, but when the Doctor and Romana arrive on Zeos they find that it is deserted and a servant of the Black Guardian, known as the Shadow is manipulating the war to get the sixth piece of the Key to Time.
This story has a brilliantly interesting concept that really keeps you going through the dullness of episodes 3-6. This is a shame because episodes 1-2 have a strong plot with some great characters and some nice arcs, but then it turns into the kitchen sink story.
The Armageddon Factor has a narrative like a 2p machine, repeatedly adding more and more concepts trying to get something worthy out of it, but while some nice small elements emerge from the chaotic mix of plot threads, nothing substantial leaves a lasting impression.
The acting is usually very strong, especially by John Woodvine as the Marshall, and Ian Saynor as Merak, by it's Davyd Harries who gives the best performance in my opinion. He's clearly having fun and constantly finds ways to ramp up the performance to something that is truly funny and entertaining to watch, especially in episodes 3 & 4.
Lalla Ward gives a good performance as the damsel in distress Princess Astra, despite not really doing a lot, and Baker and Tamm give some of the strongest performances this season. I also like Barry Jackson as Drax who shows up for the final two episodes.
This is a story with an ridiculous amount of padding. Some examples of this are the time- loop introduced in episode 4, and the shrink ray from episode 5 which just serve to extend the story by a few more episodes.
The Armageddon Factor has it's merits, but also it's faults, and while it's not quite the finale to the season we wanted, it's entertaining enough to be worthwhile.