Like Wood's book, Old Turtle, this story is more for adults than for the children they'll read it too - the illustrations (a different illustrator) are beautiful, using soft autumn watercolor tones to illustrate grandfather as he speaks with his grandchild about nature, spirit and the connection all people have to one another.
Essentially this is a book about loss, dying and eternal life. It can be a beginning point for a discussion with older children (ages 8 - 16 or so) who have experienced a loss of any beloved friend or family member.
If I had grandchildren, I'd want to have the hardcover book available for them to read. The book is written to offer room for people of nearly any faith (even agnostics) to begin a discussion the meaning of life and dying.