I was able to see this in London from fairly close up. I've long admired Laura Linney on stage and screen, and she didn't disappoint. As a one person show, she portrayed the characters wonderfully and it was always clear which person she was. The play was fine but not overly engaging or impactful for me. While watching Laura certainly held my interest for the duration, several times I perhaps was waiting for more dramatic arc, or catharsis or revelation.
Perhaps it would have worked better as a multi person play, can't say for sure. But I think if you go in with expectations that this is an intimate, subtle, low key show, Laura could be reward enough.