Several members of the family narrate their versions of the story, and usually they relate it in second person. The "you" may refer either to themselves or to someone else. Often it gets confusing as to who "you" actually is.
The story is compelling. The family members tell about their part in the long search for Mom, but mostly they look back on their life with her, recalling incidents that take on new meaning to them now that she is missing. As the story unfolds, both you (the reader) and the other family members begin to see that this woman is much more complex than she appears. She has devoted her life to her family, yet she has had dreams and fears and pains and secrets that she has kept buried her entire life.
Please Look After Mom has been a popular novel, and deservedly so. I have to believe, however, that it is more in spite of than because of the author's decision to use second person to tell her story.