So Missy turned out to be The Master.  Well fuck me, I did not see that coming. I honestly thought they were setting her up to be a regenerated Rani.

The thing with the Cybermen was a neat reveal, but it kind of gets mucked up when you look at the setup from earlier in the season.  The idea is that all the dead people are being held in this hive mind computer in modern day london, right?  But that woman from 'Into the Dalek' died on an asteroid base thousands of years in the future.  How did she get there then?  Same question for the Half-Face Man from the first episode.  He died, such as it was, in Victorian times.  Also, he was only a robot, without a real body to upgrade or a real mind to upload.  What would the Cybermen even want with him?

I don't know.  It's not making a lot of sense to me right now.

Saw the Master coming a mile away.  Missy, Mistress, Master.  I was thinking it was going to be the Rani, or perhaps Romana somehow.  Master is just too easy, and makes not a damn lick of a sense otherwise.  What's this shit about being left  to die or whatever?  10 literally begged you to regenerate, to travel with him, the last of the Time Lords wrecking every bad guy's shit!  You chose not to!  Why are you doing this you fuckwit!?  UGH.  Then there's the different people across space and time and this is making me very very angry.

If it were me I would have made it the Tardis itself doing this.  Missy is the Tardis girl from that one 11 episode and starting just after the Doctor regenerated has been plucking people, or at least their consciousness, into another section of the Tardis the Doctor may not be aware of or just doesn't think about much.  This darker Doctor is later confronted with all the people he's killed or let die in an effort by the Tardis to drive him back to a kinder, gentler way of doing things, to which the Doctor responds "I'm not gonna be made to feel guilty for saving a lot more people than you're parading around in front of me!"  Tardis is having none of that and starts threatening Clara so the Doctor has to "kill" the Tardis girl but there's consequences and Clara sacrifices herself (I'd keep Danny's sudden death and use him in this two-parter too to sort of drive Clara towards this) and takes the Tardis consciousness' place, resulting in a shift in the Tardis' behavior in the future but otherwise not meaning much except for a tearful farewell for the Impossible Girl who will always be there for him like she always has been.

But that's just me.