The play/pause media key automatically starting the Music app, suggestions defaulting to include content from paid services (hey that movie is available on Apple TV!), maps links only working with Apple Maps, searching for selected text opens Safari and disregards your primary browser, permanently enabled share menu options for iCloud and Airdrop.
Privacy settings increasingly spread out and opaquely named. No more central unique identifier reset button, but individual ones for each app placed in different submenus. Completely disabling Siri has become some sort of Easter egg hunt. Not that it'll actually stop the data outflow, though.
Aggressive surfacing of ecosystem capabilities such as proximity unlock by nearby Apple watch, wake on bluetooth or network, etc. These features were previously configurable through the GUI, but those conveniences have been removed and the features are enabled by default.
Local configuration profiles (a free, easy, local, and accessible way to configure your system) are being slowly phased out in favour of third party remote Mobile Device Management services such as Jamf or, of course, the one Apple launched not too long ago.
These new advertisements are so prominent and the implementation so obviously bad, that I'm almost suspecting them to be merely a distraction from the much more insidious tricks they've been pulling in the background.