Despite the new series branding and cover photo this book does an excellent job of covering all the companions (and, well, allies) of the Doctor since Doctor Who started in 1963 with Susan, Ian and Barbara, all the way to the 2009 Easter special 'Planet of the Dead'.
All the characters you'd expect are accounted for; the indisputable companions to the ones fans like to argue about such as Sara Kingdom or the UNIT lads, plus several quite minor characters like Duggan from 'City of Death' or Jago and Litefoot from "The Talons of Weng Chiang". Major characters have approximately a page each (depending of length of tenure this is sometimes more) with a brief actor profile at the start whilst minor characters have box-out sections at the appropriate point.
The new series characters make up about a third of the book and their pages go into rather more detail, as you'd expect. Here we get a little more info on what happened to the companions during specific episodes as well as on the Tyler, Jones and Noble families and people like Jenny, River Song and Sally Sparrow.
All the pages are full colour although some of the early pictures are colourised from the B&W originals, and cleanly laid out. Each contains a box-out with information about each of the serials, giving a few details such as the writer and broadcast dates.
There's nothing really new here for long term fans, there's no behind the scenes stuff and the biogs are brief, but the beauty of this book is pulling together the show's entire TV history in one place, not just the main episodes but cartoon 'The Infinite Quest', the CiN clips 'Born Again' and 'Time Crash', and 'The Music of the Spheres' - 'K9 and Company' even gets a mention. (I will not lose sleep at the lack of 'Dimensions in Time'!).
For new fans wanting to learn more about the earlier Doctors' companions and adventures this makes a fantastic resource though.
If I have one complaint it's that there aren't pages for the incarnations of the Doctor himself included, but I can't really argue about it only doing what it says on the cover, especially when it does it so well.