I agree, Dame Maggie can convey multitudes with just a turned back. The dialogue between the Dowager Countess and Mr. Carson was quite simple and then she just walks into the drawing room to join the family. When a genius is playing the part, these few words and actions become a master class in acting.
Another thought, Sybil's graphic and realistic death more than makes up for the 'nary-a-hair-out-of-place-bathed-in-ethereal-white-light' death of Miss Swire.
I've also found Elizabeth McGovern's Cora to be a bit wooden and I still can't get over that accent! - but, having re-watched the first two seasons prior to the premier of the current one, she has been totally consistent in speech and mannerism. I don't think EM is wooden - Edith's wedding episode and this one prove that - I just think that semi-stodgy characterization is how she and the show runners saw the character of Cora.
Like so many of you I, too, cannot wait to see how things will play out!
"...ah, gays and their wit. Hell must be a laugh a minute!"
-Evie Harris