Although this book is called `52: The Companion' it does not in fact contain any new stories either leading up to, or spinning off from, the main `52' book.
Instead it is 10 unrelated stories taken from the DC archives ranging from the modern day right back to the 1960's, with each story concentrating on a particular minor DC character who will take centre stage within the main `52' books. There are also some notes from the writers of '52' as to why they picked these particular stories.
From this point of view the book is very helpful as it helps you know more about fringe characters such as Dr Will Magnus, Rip Hunter, Adam Strange etc so you can appreciate their actions when you read the main book. However, as the stories shown here are unrelated and span forty odd years this companion itself is quite disjointed and some stories do not really work taken out of context.
I found this book helpful as I am quite new to comics and have been working my way through the main DC Crossovers starting with `Crisis on Infinite Earths'. This companion helped fill in some gaps for me prior to starting '52 Vols 1 - 4'....Continua