A top ten classic who story. Only edged out by one other story in the Fifth Doctor's era also.
This is a good old fashioned romper stomper of a story. I love the Cybermen when they are done with menace, a script with a plot and mystery, good dialogue and Saward has it all here. As many have alluded to what a thumping pace there is to this one.
The big reveal, and at the time of original viewing I would have been delighted by the first episode ending, all the scenes with the Androids are mysterious and gripping, not to mention well produced. The cave scenes are eerie and all the troopers getting wiped out is really effective as they are seemingly an unstoppable force during the first episode. Then to get the Cybermen suddenly popping up as the protagonists is marvellous, and still an effective piece of television even several rewatches later. My favourite moment in a story full of great ones.
I enjoy most things in Earthshock the characters, plot, ending, the poignant no theme music at the end with the focus on Adric's crushed star badge.
There is some great dialogue: the ad libbed "braveheart Tegan", the "mouth on legs" line. I do like the Doctors scenes when he says "always the perfect guests" and his speech about being human, anyone for a well prepared meal

Adric is even adequate acting wise, it is funny to see him jump before the Cyberman shoots the panel though

. Only Beryl Reid is out of place a bit here, but never mind.
I love all the cliffhangers, and I especially like the soundtrack and special effects when the Cybermen are smashing out of the silos and marching through the freighter, it all adds to the spine tingling adrenaline inducing feel of the story.
The Cybermen are given a fantastic gratifying outing, from the design and realisation, love the boots. To the recap of their previous meetings with the Doctor: First Doctor's human line from Tenth Planet/Second Doctors scene from Tomb of the Cybermen scene/Fourth Doctors Tin Soldiers line from Revenge of the Cybermen.
Simply brilliant.
A special word on the commentary provided by Peter, Janet, Sarah and Matthew. Really enjoyable and worthy of spending the time to hear the undoubted bond and atmosphere within the actors.