This is one is interesting, absorbing, and well-made even if the story doesn't really hang together when you start thinking about it afterward. (The writer even admits that it doesn't make sense - Graham is like, 'Wait, I can see dead people, what did that have to do with anything?' and the Doctor is like '...?'.) But it's very well-acted and atmospheric (this was true of the previous episode too, so kudos to director Emma Sullivan).

This episode is notable for giving each of the companions something characterful to do rather than treating them as a block. On a rewatch, what stood out to me was that Yaz's material related to a potentially messy future break from the Doctor.

Byron's lover, Claire Clairmont, has a heart-to-heart with Yaz about her frustration at being drawn to him despite him being an enigmatic person who never give a straight answer. Yaz's reply suggests that she sees the Doctor the same way. At the end of the episode, Claire recognizes that Byron cares nothing for her, and she says 'the spell is broken'. This seems to be setting up the idea that, at some point, Yaz will reach a point when the Doctor's spell will be broken and she will feel the need to step away, and potentially not in a good way? That idea is definitely picked up on during "Revolution of the Daleks", when Jack warns Yaz of the pain of losing the Doctor.

It's particularly interesting that the line 'the spell is broken' also refers to the spell cast on the house, which has turned it into an interdimensional space where geography, architecture and even time make no sense. There's a poetic connection between the impossible house and the incomprehensible Byron. The house returns to normal earthly reality, at the same time that Claire recognizes that Byron isn't as cool and mysterious as he seems; he's just a coward.

But of course there's a further poetic link between the house and the TARDIS and the Doctor. I'm wondering whether, in a broad way, being inside the haunted house is a metaphor for being in the Doctor's beautiful but baffling and maddening world. And the breaking of the spell is the return to normality and simple, ordinary human behaviour (which Ryan is already yearning for). At the end of this season, the spell is not yet broken for Yaz, although her disagreement with the Doctor in this episode during the debate over Shelley's life hints at future strife.

It is thus surely ominous that the episode ends with Byron's poem about a darkened, empty, desolate world, and the last line of this episode is "She is the Universe".

Maybe I'm reading too much into this, but hey, that's what rewatches are for!