I've been using it since Plasma 6 came out so about 3-4 weeks.

Overall, it's been a very negative experience for me. The main problems have been:

• Random scaling issues in apps: some apps show a slightly smaller cursor, other show a poorly upscaled one, others have random rendering issues like lines remaining on the screen after an option is no longer highlighted (gimp, libreoffice, many others), some apps have random flickering of parts of the UI, some apps no longer scale at all or are scaled twice. Plasmashell itself has blurry icons on the desktop but all other KDE apps don't. I know fractional scaling has always been problematic, but it has gotten worse to the point of being almost unusable
• Random crashes of GTK apps when using the wayland backend. Some GTK apps don't even start and segfault immediately with a wayland error in the terminal
• Some apps like okular and libreoffice lag like crazy or outright freeze when scrolling
• Some games not capturing the cursor properly (Proton)
• Inconsistent font rendering, some fonts look fine in some apps and atrocious in others
• Issues when resizing or moving windows, some times they "jerk" off the screen or resize to a very tiny window and I'm forced to use key combinations to resize them again
• Random issues with window decoration not appearing in some apps but randomy appearing for things like context menus

This is on a full AMD system with Arch Linux, the latest kernel and mesa-git. I hope for KDE's sake that there's something broken in my installation because I can't believe the KDE team released Plasma 6 in this sorry state.