• It's slower then 10.
• They recently disabled the old configuration screens, meaning you have only the fancy looking broken settings. Try to remove a Bluetooth device. You can't. "failed to remove device". It can't forget the Bluetooth data. This is one of many flaws. Many settings are gone now.
• it's impossible to remove Edge now.
• there are ads within the OS.
• they stopped support for several apps, for instance to use the Xbox kinect as a 3D scanner.
• it's now harder, sometimes impossible, to boot from a USB as win11 has too much control over the bios and makes UEFI sometimes impossible to use. It automatically boots into windows, even when told otherwise, and "repairs" the changes made.

I can continue for hours why win11 sucks donkey balls. Recent news from MS about their plans for win11 are also very troublesome. As well as the paid subscription for win10 for security updates. Like, wtf! I have 3 machines running win10, so I need to pay 90 a year? For real? Just so I won't have to use the win11 aids.

I mean for one it supports a lot less hardware. Second it's significantly less reliable. Third it has thing like Co-Pilot built-in. I don't know how people aren't criticizing it more frankly.