That was by far, my personal favourite of the season to date. What an extremely well written episode! We finally got some incredible character driven drama, all encompassed within an interchangeable state as the direction of the episode itself flicked from drama, to tension, to awkward moments, to comedy - all in the blink of an eye. I really can't praise this episode enough.
The new character dynamics of the Doc, Clara and Danny was incredible to watch (they shouldn't have waited so long to do this - and my God, THAT is how you do bickering, please take note Robots of Sherwood) the Doctor was simply brilliant in the episode from start to finish doing his own thing and pulling Clara along (rather than Clara leading the charge) and speaking of Clara she's finally coming into her own! I now actually like her.
And that's forgetting all the references.
More of this please. This season has been up and down, but if we get more of this, I'll be extremely happy.