Austin and Barbara, I'm reluctantly going to agree with you. We had a Triffids episode, then a Fantastic Voyage episode (Who had already done one of those, with Tom Baker). Running out of ideas? Then the finale was a kind of high-tech Armageddon with even the kitchen sink thrown in. The only real fun in that episode was provided by Missy, the Master in some female incarnation.
Odd thing...in the opening credits, Jenna Coleman's name came first, before Capaldi's. I don't remember ever seeing a companion listed ahead of the Doctor before. It looks as if her time with the Doctor is over, but she made a fetching Lydia in Death Comes to Pemberley.