Very impressed.
I was not familiar with Charlotte Riley until I saw Easy Virtue recently. I thought she delivered an excellent performance in a somewhat small part: understated, but communicating the character's deep feelings and character effectively. Frankly, I felt she provided a welcome contrast with some of the other performances, which were somewhat stereotyped and over-the-top.
In short, I could relate to and care about her character, Sarah . . . was hard for me to do likewise with the others, except perhaps Colin Firth. (The butler was very funny, however.)