This is a great book that adds lots and lots of new information and options for a Doctor Who game. Like all of the line, this book is pretty and easy to read. As a fan of classic Who, I was very happy to see that the book covered all the Doctor Who timeline both in the text and the illustrations.
The book includes cultural and historical information about Gallifrey and the Time Lords, answering a lot of questions and offering tons of plot ideas. It's worth reading even if you don't play the game. Not only do we have the big historic events (like the Dark Times and the Time War) but we have information on daily life on Gallifrey.
Next is a whole chapter on creating Time Lord characters, starting with tips for getting around the "last of the Time Lords" bit. This fixes the only real problem I had with DW:ATS, namely everybody (naturally) wants to play a Time Lord. This chapter includes a step-by-step process for creating Time Lords with background information (like the Academy and naming conventions) and good and bad traits. Most of this information is drawn from the TV show. There is also a lot of information on regeneration. Regeneration is handled randomly with rolls and tables increasing or decreased stats and changing physical appearance and personality. I'm not convinced this is the best way to handle regeneration but it does reflect the sometimes extreme nature of regeneration.
Chapter 4 covers temporal tricks in a lot of detail (possible too much detail). There's paradoxes, and vortex manoeuvres, and nexus points, plus a plethora of temporal gadgets. This chapter tries to catalog and understand 30 years of Whovian craziness, and it does a really good job (particularly since I strongly suspect the Who-verse doesn't make complete sense). But it also adds lot of complexity to a game.
Chapter 5 is dedicated to TARDISes, their history, systems, and uses. There are details on almost every aspect imaginable from the "desk top theme" to "spatial overlap" and the Cloister Bell. There are notes on ancient to advanced TARDISes as well -- most exciting of all -- rules for creating a TARDIS complete with good and bad traits (an insatiably curious TARDIS may nip off to have adventures on its own!).
The rest of the book is given to "GM-only" information: dark secrets of the Time Lords, hidden technologies, and famous and infamous Time Lords (like the Master and Romana!). While there's lots of great information here, it won't be "GM-only" to anyone familiar with classic Who. There are chapters of adventure seeds, ideas for setting games during different periods of Time Lord history, general GM advice, and even more advances temporal phenomena.
Finally, there is an extensive and helpful index, as well as Time Lord and TARDIS character sheets and helpful reference cards.
As I said, there's a lot of information here, not just setting but rules: new rules, modifiers, stats, and charts. Enough so that incorporating all these rules could alter the feel of a DW:ATS game. While the system is still simple, this supplement adds lots of fiddly bits. Without a light touch, all these new details could bog down a game (something the book addresses). These is a great book to dip into, cherry-pick, or even obsesses over, just like Doctor Who itself.
[5 of 5 Stars!]