One area where it is peculiarly lacking is actual references. There is no chronological index, an omission explained by lack of space and the availability of the information online, but this leaves a sort of vague impression about the details of the show's history. Few calendar dates are given other than the year. Citations given in an appendix are incomplete - where, for instance, can we find the 2008 online debate with Ian Levine cited on pages 192-193? The back cover blurb promises "unique" interviews with Barry Letts and Philip Hinchcliffe, but this actually means extracts from pieces previously published in Dreamwatch, so not all that unique then.
I'm interested at least to see someone else pick up on the possible importance of the 1943 Tommy Handley vehicle Time Flies as inspiration for Who - I wrote about this two years ago, and Robb cites an article making the same point by Phil Norman and Chris Diamond in TV Cream's Anatomy of Cinema (which turns out on further research to be a book on forgotten films published in 2007).
However, I think even completists can skip this one fairly safely. (And I wish I could remember why I decided to buy it.)