I bought the book and finished it recently.
I don't regret my sale as there are lots of fresh ideas in it which I find interesting.
However I also noticed that some mistakes which were already in the book of Malianuk are again popping up in this new book (see more info about this in https://www.chesspub.com/cgi-bin/chess/YaBB.pl?num=1374899483/60). Demuth also writes that he consulted the book of Malianuk and clearly he has just reused some lines.

Some other observations I had was that the main-line with 7...c6 only consists of 65 pages of the 470 pages. So there is a gigantic effort done in covering side-lines. Especially 2.Bf4 and 3.Bf4 are discussed in depth. I remember almost a decade ago here on chesspub this line was considered as rubbish and not dangerous at all see https://www.chesspub.com/cgi-bin/chess/YaBB.pl?num=1320337103/0. Things have changed dramatically. I almost lost right from that opening against a 1700 (despite having myself +500 elo more) last summer and Demuth thinks it is not easy at all for black.

Yes.