Another case of critics being out of sync with public opinion.
Yes, it is a bit heavy handed in places but it is navigated well by the stellar ensemble cast. That said, Helen Mirren would have been more convincing in her own accent. Keira Knightley had a nice almost English edge to hers making it sound deliberately inderminate rather than Helen's which just sounded bad.
The premise of the piece will be more easily identified with for those who have suffered devastating bereavement. It covers many of the thoughts one has and how abstracts become real in those times.
I think the critics missed the point.