I really like that the book itself looks like a old library book complete with a "Book on loan" stamp and a ripped binding. The only mention of the real authors JJ Abrams and Doug Dorst is on the cardboard slip the book comes in.
If you left it on the bus whoever picked it up would think it really is a old library book someone wrote in.
The one thing i had to learn is there are old comments and newer comments left in the margins the old ones are in black and blue or light grey and the new ones are orange, red and green but its all the same two people just a different timeline. Some of the comments help you understand whats going on in the main story a little more to.
Cant say to much about the actual story without spoiling much but its a very deep book and super interesting. However some of the deepness makes it hard to read sometimes. I know I'll be going back and reading the comments in the margins a second time after I read the first story an thats fine some of the fun is learning how you want to read the book.
One example of the deepness is that the girl is talking to the guy in the margins about how her parents wouldn't understand her about something and then there is 2 papers left in the book about that back story on why her parents wouldn't understand her/are over protective that also ties into the original story and their main story.
Highly recommended if you like mystery's at all you could totally forget the second story and still enjoy the first one or the second without reading the first but reading both together is a great experience that im finding really hard to put down.