There are spoilers in this review be warned!
The simple story of the episode is the Doctor suspects that when anyone is alone they have evolved defence strategies like talking to yourself to combat a unseen creature which has evolved to be the best at hiding. This episode is a time loop.
The Scare Factor is a 100!!
The use of sound was highly effective in this episode as it tackled the question of how do you show a creature which can't be seen. The timing of louder bangs and soft sounds for the creature and characters imaginations was excellent. The scenes has creepy Colour lines and mysterious tones which added to the overall creepy feel of the episode. The unseen monster was an brilliant idea expertly executed. Children need to watch behide the sofa for this one!
Danny Pink is still awkward but seeing him as child bring greater audience understanding of him. Clara and him just are going to be that awkward couple with rubbish timing.
Clara took the lead on this episode and she really is one of the strongest and time y whimey companions to date and most influential on forming the Doctor.
Clara leads the plot forward based up the Doctor idea which allows for him to have backseat control.The audience relates more to Clara than to the Doctor at this point. Her very awkward soap romance with Mr Pink feel forced and is very cringe worthy but can be funny.
Peter Capolid's performance is excellent as grumpy serious old man. But the audience has a weak Connection to him but this changes with the revelation end of the episode. As it appears he and his fourth wife River Song both share growing up in childs home.
Clara and Danny are part of the Doctor's family?
As they seem to share a Family heirloom!
I give this episode 4 out of 5. It developed all of the characters well but the soap love story between Clara and Danny can be funny but it was disconnected from the main story in this episode. Creative monster and MORE DOCTOR BACKSTORY!