Georgiou fights for survival in the mirror universe.
This is an enjoyable episode with some good mirror character moments and good links to the Trek universe.
The plot is full of the entertaining backstabbing and deception seen in most Terran Empire stories, whilst the reveal about the doorway that comes relatively late on is pretty good, but not exactly surprising.
This will probably go against the grain of some, but I think one of my favourite aspects of the episode is the time spent with the mirror Burnham. I found it an interesting change to see her this way and there is a bit of emotion thrown in for good measure which hopefully annoyed all the anti-Burnham mob. She's a passionate character in both universes, which is pretty consistent characterisation.
I like how the arc within this episode finishes for Georgiou and the notion of a time period prior to the universe splitting into prime and mirror versions.
My only gripe was the excessive sentimentality at the end, but that is a matter of personal taste for a cynic like me.
Michelle Yeoh, Doug Jones and in particular Sonequa Martin-Green give strong performances. Martin-Green plays both versions of the character perfectly.
For me this is a 7.5/10 but I round upwards.