I'll start by saying, this was a good episode, though slightly different from the others in this new series. For once, it seems that the writers finally found their feet, and have learned to write stories for this type of Doctor. Also, Clara and The Doctor's relationship is becoming stronger, and she has a lot more to do than in previous seasons. That said, this whole let's separate them and let them found each other again is getting old.
This highly anticipated episode, The girl who died, with Maisie Williams, answered one of The Doctor's own questions, which was great. It was really awesome to get flashbacks of another episode which marked a lot of The Doctor's character in the current run of New Who.
I wasn't overly excited by the monsters, but I'll say I was super impressed by the sea creature created for the episode. It seems that it ate most of the budget because well... the spaceship leaving was a bit of a let down.
The end of the episode brings a few more questions, and leaves it open for next week's second parter, and the return of Maisie Williams. I can't wait.
So brace yourselves for the trailer of The woman who lived.