The Nethersphere. Scary idea, being conscious. Find Seb an amusing character, with his Ipad. As for Danny I was surprised to find out his secret of accidentally killing a child, brings a lot to the character. Lot of drama, seeing him face the child, and Seb offering him a chance to erase emotions.
The reveal... The Cybermen were already known but of course good publicity. I didn't realise the beings in the tank were them though. Dramatic as the dark water lowered and the Cybermen are revealed, along with Clara's reaction to the tank in the office. Nice of them to recreate one of the most famous scenes of 60s Who, Cybermen advancing at St Pauls Cathedral. As for Missy... When you go on TV Tropes WMG you think up weird ideas. Maia of the Gold Guardian? At least I wasn't taking Freud's wonder drug. And I did have the idea that the Nethersphere was the Matrix. I wonder how Master able to gather characters from other times.
So, Mary Psychopompins was the Master. What a twist! A lot of people worked that out but still dramatic reveal. Hope we find out how they escaped Gallifrey. As I put down on TV Tropes S8 WMG he (or perhaps she) may have escaped through the crack in TTOTD. Found out in book last year Harvest of Time that one of Master's incarnations female. Interesting. The part where Missy pretended to be a welcome droid was quite amusing. Gomaz plays that pyschotic nature well, such as telling Chang how sorry she is she will kill him. And the usual glee with revealing her identity.
Finally, after three years, a two-parter. Moff said in DWM the problem with two-parters is the second part living up. Which I certainly agree with. (TSE/JE) No next time trailer. Know that UNIT will be here next story. Will Doctor have to destroy Nethersphere and kill Danny to save world? Overall good first part. Slow-paced but interesting. And finally an alliance between Master and Cybermen (in The Five Doctors that wasn't the main event). Look forward to part two.