I'm not sure why the previous reviewer confused this product with the BRP Quickstart, but this product does contain 400+ pages of role-playing goodness. This book is a solid foundation for a DIY game, in any genre: fantasy, science-fiction, horror, historical, post-apocalyptic, or mashups yet to be devised.
The core system will be familiar to players of RuneQuest, Stormbringer, Call of Cthulhu, and nearly every other game Chaosium ever printed. However, the author has included a plethora of optional and variant rules culled from BRP's rich history, from hit locations and strike ranks to EDU and Sanity from Call of Cthulhu, to skill category bonuses and skills over 100%. (There's even a handy checklist of all optional rules for GMs to provide players.) On the paranormal side, the book presents two different magic systems ("magic" from Magic World and "sorcery" from Stormbringer), mutations, psychic powers, and super powers, Allegiance, and creatures from prehistory, mythology, and possible futures. Anyone who wants to emulate a specific game, e.g. Call of Cthulhu, can.
Granted, the book is a little weak on science-fiction, but SF is such a wide field that no reasonable-sized book can encompass them all and other genres too. Likewise, it doesn't contain every creature ever made, but it has common ones and enough examples to extrapolate from. Also, don't expect a detailed treatment of every genre and historical period ... but the GM section includes a rundown of broad historical periods. There's only so much that can fit into 400 pages, after all.
For a straightforward campaign in nearly any genre, this book is all you need. GMs with more specific or outre ideas might need to do a little work ... assuming they can't borrow from previous Chaosium RPGs, Mongoose's RuneQuest, or fanzines and websites, which use practically the same system.