People really don't like to hear bad experiences, judging by the downvotes. But I agree it's a really bad upgrade and it's not ready for use at all.

My experience with Plasma6 upgrade:

• A new, but empty, floating panel was installed and my existing panels all got mangled up so I had to delete everything and make a new panel
• SDDM doesn't use my selected theme and displays a huge virtual keyboard that blocks half the screen (changing themes doesn't help)
• Icons are broken and ugly (changing icon sets didn't help me), mainly because "missing" icons are replaced by black icons on a black background
• Kvantum doesn't work, so I can't use my theme
• Conky always stays on top and breaks the desktop
• The screen goes on standby while watching movies
• Win+Tab to get grid view no longer works
• Terminal shows squares instead of unicode symbols
• Shutdown/reboot/log off no longer works from the start menu, I have to manually run sudo shutdown
• Scrollbar behavior got broken (at least this is fixed with a setting)
• It's trying to set Wayland to standard even though it still doesn't work
• Animations don't work anymore
• Hovering over a start menu entry (to open a menu) also opens a "plasmashell <2>" on the taskbar

Don't upgrade if you haven't already.