Back in the early 80s when I was an avid comic collector, I devoured the mini-series "Official Handbook of the Marvel Universe," a detailed guide to just about every superhero and supervillain on the Marvel roster. I'm currently a fan of "The Walking Dead" trade paperbacks, and this is a good reference for the series.
FYI: Just in case you're looking for information on the TV show, this book doesn't cover that incarnation of "The Walking Dead" (although a marketing blurb on the back calls the Survivors' Guide a "can't-miss supplement" to it). We're dealing with the comic book saga here. That means you'll see bios for characters from the very first Walking Dead comic all the way to the Alexandria storyline (around issue 84 or up to the events in the "No Way Out" Volume 14 TP).
The format is somewhat similar to (although less detailed than) the Marvel Universe handbook mini-series. Each character gets a mug shot, some action scenes, vital statistics, first/last issue number appearance, and an essay appropriate to their longevity. For example, a short-lived character like Arnold (one of Maggie's brothers) gets one page, while a mainstay such as Rick rates multiple pages of exposition.
As with any character-bio one-shot or mini-series, "The Walking Dead: Survivors' Guide" will grow more obsolete as time goes by ("We Find Ourselves" Volume 15 TP is already on the stands). But it's a fun look back for long-time fans of the comic series and a helpful catch-up reference for newbies.