I just happened across this book at the library the other day. It's basically a book of writing prompts and random tables that are designed to help you flesh out details about your character that might not normally come out in the course of playing. I've read articles on this topic in the past, but never saw an entire book about it, so I was intrigued.
The thing I like about resources like this is that they are useful beyond RPGs. Any kind of writing can greatly benefit from spending some time thinking through the backstory of the characters, and the systems that operate in the world. Even though most of these details will never come out in the course of playing or storytelling, they help to inform the events and motivations that drive the story/game forward. Doing that kind of prep work can't help but make the story more engaging and relatable.
This book specifically seems to have a good breadth of information, but not a ton of depth. By that I mean that there are lots of different aspects of the character and world to be considered, but most of the tables are only d6 rolls. There aren't a lot of variations on the characteristics in this book. So I would use this book more as a guide for things to think about, not as a way to create a character.
But still, based on my preliminary scan through this book, it's definitely worth a look. Especially if you can find it at the library.