The point of this book is to tell you how Four we knew in the trilogy was built, for he was just Tobias Eaton. This book is sectioned into 4 : The Transfer, The Initiate, and The Son, which are all set before Divergent and The Traitor is set during Divergent. There're 3 exclusive scenes as well : "First jumper, Tris", "Be careful, Tris" and "You look good, Tris". This book is fast-paced, and a very light read, as I savoured it whole within 2 hours.
I really enjoyed the changing view, as I got to be in Four's shoes (though I really don't think I could be in his shoes within the entire reading, well at least some of the time). It was good to see the additional character development on the side characters, especially on Max and Eric. I was glad to finally know what's up with Eric and Four and how did they become frenemies in the first place. There's this friendship between Four-Zeke-Shauna that I enjoyed as well. The problem with this book is that it's not a book; no matter how many times you try to connect the 4 chapters, it won't happen, as they are all just notes on the backstories, so just enjoy it for what it is.
Overall, Four : A Divergent Collection is a must have for all Divergent fans out there. As for those who aren't, this is still a fresh good read, though not really recommended to have as a physical collection.