The "Notes" is like a missing piece in a clue. It helps the reader understand the story, and it gives the perception that a reader knows Norman Bowker to a personal level. It was written after Norman died which kind of serves as a memoir of a person who has done great things but still considered himself a failure.
My appreciation of the story grew after reading the "Notes". I'm grateful for the added information and knowing what's real and what's not. The "Notes" showed a connection between the characters and the people they are based on in real life which made the story more heartfelt to the reader.