1) New Who is strongly authored (by RTD and now Moffatt) which makes it very different from Old Who; NB though that the credit for this authoring is shared by others (notably Phil Collinson and the BBC's upper hierarchy)
2) New Who's writers are themselves long-term Who fans; but this does not mean that they have a harmonious relationship with the fan base.
3) Time travel, though obviously central to Who, is not really used in an sfnal way in New Who (the weakest of the chapters, I thought)
4) Monsters are even more central to New Who, both as spectacle and as moral lessons.
5) New Who cannot clearly be categorised as 'quality' or as 'non-quality' TV (includes a very interesting passage on how Christopher Ecclestone's comments on the show undermined RTD's attempts to mark it as 'quality').
6) Murray Gold is one of the key creators of New Who (also the occasional use of pop songs in the show is mildly interesting).
7) New Who has managed to become both 'cult' and "mainstream' (NB this is quite a different distinction to 'quality'/'non-quality').
I thought the two best sections were on Christopher Ecclestone and Murray Gold, but there is lots more here too.
By writing this book, Hills appears to have hoped to update Tulloch and Alvarado, but I think has done a better job. It's not quite as magisterial as the Time and Relative Dimensions in Space collection (to which Hills contributed the chapter on Big Finish) but way better than the books I've read on Who by Robb, Newman, Chapman, Couch, etc.
I was a bit annoyed at first at yet another book which banishes footnotes to the end - why, with 21st-century typesetting technology, is this still considered an acceptable way to publish? - but fortunately most of the footnotes are simply references to other work, most of which I have already read (though I am still irritated by the handful that do have substantive content, marooned hundreds of pages from the statements they are illuminating). So that turns out to be a minor gripe.