Good touch gestures for window and desktop manipulation, multiple desktops easier and better, tabs supported in more places (e.g. File Explorer and Notepad), better behaviour when connecting and disconnecting external monitors, some nice window positioning, better WSL integration, etc. Nothing huge, but lots of little improvements.
The monitors is actually broken for me. Windows disconnects my monitor even for something as small as alt-tabbing from a fullscreen game and refuses to reconnect it till I unplug the monitor and plug it back in.
Proper HDR support. What's the point of fancy OLED screens when you can't use them?