I get the point they're making but I really like FAQ's. They help with the "know what you don't know" sort of thing at a glance. Perhaps not useful on a gov.uk site, but generally speaking.
I personally think it's a big improvement over what it was before -- on macOS at least. On macOS, Firefox had always felt a little bit off. Nothing too egregious, but just enough to make it slightly unpleasant (like the non-native context menus). I feel like that has been resolved in this update.
This is actually amazing! Completely changes the feel of the browser. It makes much more of a difference than I imagined it would. It feels so so much better on Mac.