It was everything a 'Who' should be. Taking the ordinary and making it extraordinary in a very creepy way. There will be children across the country who sleep with the lights on tonight!
For me, this is the best episode since the extremely creepy 'blink' (doesn't Alex Kingston look like an older Sally Sparrow?... no relation, I'm sure, Sally Sparrow would be a fantastic companion...)
There are a lot of ends to tie up, I just hope that the second episode does it justice (and that they finish with something to really make bedtime tricky next week - as they did in Blink with that statue montage).
Stephen Moffat has written another corking episode, I just hope that he can keep the standard this high when he's show-runner. Personally, I'd love to see extended stories (not just one and two parters) - so it's nice that the ground has been laid for future storylines with Alex Kingston (who was great today).
Don't mind me though, I'm still missing the big giant doctor head in the titles of each episode.