This is probably the high point of the series, for me. A great, creepy episode; some real character insight and development; clever plot ideas and a really great monster. Doctor Who at its finest. Which is what I remembered from the first time around:
Probably my favourite episode from the series, so it has a lot to live up to. Playing around with the dimensionality of things, with monsters that only live in two dimension, while The Doctor is stuck in the Tardis, because the outer shell has materialised in too small a size. Good, creepy monster. Great settings and a good cast of characters.Given that the Tardis' outer shell is a different size to the interior, it strikes me as amazing that nobody has considered making the Tardis the wrong size before. If there's one thing I love about the Moffatt era of Doctor Who, it's that he is very clever at expanding on elements of the characters and lore which we take for granted. His series have been full of little insights, such as the Doctor's description of assistants as "carers": "She cares so I don't have to" or Matt Smith's "Make the whole of time and space your back yard and what do you have? A back yard."
Clara's experience of walking a mile in the Doctor's shoes grows to two miles in this story, with the Doctor completely trapped in the Tardis. What's great about this story is that t never feels like the Doctor has been written out for an episode, like in the classic era days when the actor was due a holiday during the filming schedule. He remains ever-present through the interface with Clara.
The only let-down for me in this episode is that the Doctor's view of Clara's eyes are not consistently point-of-view shots. There are some images the Doctor sees on his monitor which are clearly static or tracking camera shots, something humans don't really do with their eyes. Having established the convention, they should really have stuck to their own rules.
Yet it's an episode that does pretty much everything else right. There are a great group of characters, who get a little bit of space to present themselves (for some reason I'm put in mind of the excellent ensemble cast in Journey to the Centre of the Tardis). The monster is excellent - a scary idea realised brilliantly on-screen. So well, in fact, that still images really don't do it justice. It's the flickering, shambling motion that really sets them apart. There's genuine drama for the main cast and it just entertains throughout.
It's only let down slightly at the end. Capaldi gives one of The Doctor's customary rousing speeches and challenges to the invader, which is fair enough. But there's an over-theatricality in the need to give them a catchy title. The Doctor says "I name you: the boneless." It's as if the marketing department, or gatherers of DW lore really couldn't cope with having a canon monster without a name for reference. Ah, well.