Simple example of the newly poor UX. I try to start notepad to jot down some scratch. It sluggishly reopens whatever it previously had open (e.g. from before a reboot)...and in doing so, doesn't actually create a new document for me.
Then turn off session resuming? Turn off Copilot? They're options in the Settings menu, if you don't want them.
That was the straw that broke the camel's back for me. For my use case, it rendered Notepad unusable.