The last arc with the silence ahd been so overblown that the resolution seemed just dull. But here the red line was visible but not so annoying and consequently the finally had me sitting on the edge of my seat.
And I very much liked the Clara of this episodes. I maintain that she was written extremely unevenly throughout her seasons. The writers didn't really have a strong concept of her and so she was a bit different every time and sometimes seemed empty. But here, not at all! This Clara worked for me and clicked emotionally.
A sad ending but a very good one, with her protecting the Doctor from the truth, sometimes he routinely does to his companions.
Capaldi was at his best and I love his Doctor, he can stay a good long while!