I read it a few weeks ago. The only new aspect for me in it had to do with the possibility that a very large percentage of the young girls who seek transition in fact have never kissed anyone, never had a date, are virgins and so on, yet many describe their desire to transition from at least partly a sexual angle.
I have seen the latter quite a bit on various online sites. Shier argues that this is because the teens now live online rather than in the real world so they have replaced socialising and dating with online activities. Also, girls who lack friends and social standing are drawn toward transitioning because it opens up a subculture which supports and celebrates them and turns them from outcasts into central players in that subculture.
The author's conservative views appear toward the back of the book , in my opinion.
The flavor of the book is very much that it is being a woman or a Lesbian which is now made so unattractive that girls don't want to go there when it looks like they can simply turn a switch and become boys, but in the last chapter(s) the author goes back to essentially innate thinking about sex roles and how certain occupations are more suited for women while STEM is for men but the former should be equally valued (are not in pay, of course) and so on.
This really goes against the main themes in the book which are very much about the re-emergence of women's roles as largely sexual and the clear rebirth of retrogressive thinking about what a man and a woman might be. Short hair equals men and so on.