Without divulging too much of the plot, I'll give a summary of what was so perfect about this episode.
There was a wonderful lack of fighting scenes this time round, yet tensions ran so much higher than ever. The lack of a soundtrack throughout the episode gave such an eerie setting you'd think someone was about to die (they do that a lot with this show). The production staff made a fantastic use of stills to summarise a plot point (see the very last scene) and still had some fantastically fluid animation to make sure you were always immersed and never taken away from the story.
The voice actors all did a very, very special job, even watching without subtitles I was able to tell what they were saying (bare in mind I don't understand Japanese) and I genuinely thought at several points that the VAs were put under physical pain to produce such terrifying and perfect sounds.
Hiroyuki Sawano was wonderful as always with his accompanying soundtrack, and did a great job rounding off the episode with the renaissance-like image at the end.
Very rushed review but I loved this episode, probably the best single piece of TV I've seen to date. 10/10