Well, I made to to the theater yesterday. It was almost full, but I did buy my ticket on line.
Simply put, Dame Helen IS The Queen! Her performance was excellent. She walked, talked and conveyed the Queen's personality very well.
I thought that the Queen Mother was also played very well. Since she was 97 when Diana died, she was in decline. Even the slight angle of her head was down, as it was with the QM. She also provided great humor.
I liked Tony Blair's rebuttal to his speech-writer. I thought that it really showed Blair's growing respect and understanding for HM.