I quite enjoyed the build up throughout the episodes to the final identity of Missy. Gomez bought to the the role the kind of zany but deadly antic behavior that John Simm portrayed. If I understand correctly was the Nethersphere inside her TARDIS the whole time. And I have a theory that Missy is an earlier incarnation before the events of Utopia.

I thought at the last part as the chorus begins singing and Martha marvels as the Doctor describes his memories of his home was good scripting. And the kittens were a nice touch as well.