Interesting that most of this boils down to 'its different'
I'm not sure that's fair. I'm reading three types of complaint that aren't simply "it's different":
1. It takes more steps to do things. That's not just different; it makes the UX for those tasks objectively worse, at least for a person who already knew how to do them.
2. The UI is designed for touch and is inefficient with a mouse.
3. Useful functionality, such as being able to have certain types of applications side by side or run multiple instances has been removed.