It would be tempting to say you should donate and get this book just because it's a great cause. But actually the book itself is really rather good. Here's a little bit on each story:
Epilogue- Warsmiths by Matt Fitton: In typical timey-wimey fashion the prologue and epilogue are the wrong way round here. This story sees the War Doctor confront someone trying to stop the daleks from ever existing. It's set just before we meet the War Doctor in "The Day of the Doctor" and is an excellent start.
Karn: This tells the story of the War Doctor's first moments of life after his regeneration in "The Night of the Doctor". It's a bit bleak but pretty wonderful.
Crowsnest Past by Warren Frey: Not very war-y, this is the War Doctor doing a typical Doctor Who story involving banking-based monsters set in Canada. I wasn't too keen on this story. It's fine but I felt any Doctor could have been involved here, and the book is focusing on the War Doctor.
The Eight Minute War by Lee Rawlings: The War Doctor assembles an army on board his TARDIS but things don't work out too well. This is one of my favourites of the collection and is a story that only feature this incarnation of the Doctor.
Everything in its Right Place by J.R. Southall: A weird land of fiction type story that features Alice from Alice in Wonderland. I fear this type of story has been overdone in the written world of Doctor Who and there's little that makes this particular story any better than others.
Corsair: The War Doctor works alongside fellow Time Lord the Corsair. It's fun to see more of a character only mentioned in the actual show.
The Ambassador From Wolf-Rayet 134 by Kate Orman: An ambassador for an alien species that is time-sensitive visits Gallifrey. The War Doctor is on hand to ensure things run smoothly. An interesting alien species and interesting to see the War Doctor be war-like without having to be violent.
The Amber Room by Simon Brett and John Davies: A new room in the TARDIS! And a human soldier meeting the War Doctor. A really enjoyable tale.