This series has been a complete chore for me up to now.
I like the interactions between The Doctor, Bill and narcolepsy - love all of that - but the actual stories and adventures are tedious and worn out.
That part at the blackboard where The Doctor explains about space - that was brilliant. Capaldi is that magnetic that you could have a whole episode of him just at that blackboard explaining stuff and it would be brilliant. Instead we have to go to a space station and deal with space zombies. And somehow that's more boring than a man giving a lecture at a blackboard. Capaldi's just too good an actor to be wasted on trite generic sci-fi fare - his best moments are his intense or quiet character moments - he's wasted with this generic stuff.