i just deleted my old post and added this instead:
my initial anger about the new GUI has gone. Since i moved from 24" to 27" displays with 2K resolution, Cubase looks - without exaggeration - really fantastic and indeed much better than Cubase 9. It’s really worth to upgrade your display(s) if you’re in the same situation and dislike the big fonts etc. on smaller screens. For more info and screenshots see my later post:
One point of criticism still is that there was no note about the GUI being optimized for larger screens (only), and/or that users can’t switch to the old GUI as a preference.