I thought it was a good episode, as Woolly says with both the horror and the funnies that a good episode often has.
There were definitely some good phrases used:
Prof: Doctor What?
Doctor: If you like.
Doctor: Ignorance is Carlisle.
Clara: Sharks are quite eaty.
The whole spiel with the Tardis' Voice Visual Interface, especially her "Whooa" when she first see's "herself". That almost makes up for referring to Whisky as the 11th most disgusting thing ever invented. Heresy!
The colouring of the episode was interesting. Clearly it often had to be dark, to allow for the mystery and occasionally spooky item in the background, but there was also often a very brown tinge to things, and with the background colouring, it all made for a very, possibly slightly clichéd (deliberately I imagine) seventies feel. Neat.
I did have a few minor quibbles however.
There was really no explanation for the cold, and why it was so localised, even to the extent that the Doctor marked it on the floor, and that bit of floor then "smoked". Similarly with the heart of the house being in the music room, why did all of this stay in the same place, when Hali actually seemed to appear in various places (over a small relatively localised area).
The candles being blown out wasn't explained, unless that was purely a random draft that happened to be coincident with a spooky part of events.
Why did Hali appear to be able to talk, and even move to an extent, when we saw her to start off with, when it turns out that she's experiencing time very much more slowly, hence all the images of her being the same throughout time. Either she's not in sync with the present, or she is. They can't have it both ways for dramatic effect, unless they explain it as something relating to contact with Emma, although there are lots of holes in that explanation as well.
If the universes are allowed to be in sync when "connected" by Emma, why do they stay in sync when she looses contact, but the Doctor is still there. On the basis of the story, it should be a fantastically long period of time later, when they reconnect.
Was the "Help Me" on the wall in ice put there by the beasty in the house? It doesn't seem appropriate that it was Hali, since she wouldn't have any control over the physical world in our universe.
I'm not convinced by the Profs age. If he's taken to be the same age as the actor playing him (47), then he would have been 18 in 1945 (the episode is set in 1974), which would have been awfully young to have done all of the things he was supposed to have done in the war, even allowing for some latitude in the character's age.
The Doctor refers to the beasty in the house as being her, and the one in the pocket universe as being him, which seems a bit sexist, since he barely knows what they are, let alone their genders. It's also not clear how they've survived the apparent disparity in time sync, unless they're something which has the ability to perceive and experience time differently to the rest of us.
The bit with Clara going on about "The entire life cycle of Earth ... and you're OK with that? ... We're all ghosts to you, we must be nothing ..." was clever insofar that it gave the Doctor the chance to use phrases like "You are the only mystery worth solving", which alludes both to her and the whole of life, as well as the implication that maybe she is a ghost, and that he has seen her graves, when asked that by her! However, it didn't ring very true for something for her to say, since up to now she's mostly been very smart and obviously thought things out very clearly. Her sudden apparent inability to have not thought about the implications of a time machine, which will have allowed him to have seen the entire universe from start to finish (let alone the very recent life of the parochial corner that is the Earth), doesn't really seem appropriate, and to me didn't seem very like her character.
Still, aside from those minor points, it was very good and I enjoyed it immensely.
