There are improvments, but none that I can associate to the UI, which I still think is a massive regression.
Being able to copy paste from the console. SMB3 (i.e. offering encryption if properly configured). Virtualization was a major leap forward in windows 8/windows server 2012. Http2 support in IIS.
What truly turned me off of Windows 10 was something small but very symbolic. On past versions of windows, if you want a shortcut to, say, Notepad on the desktop, you open the start menu, begin typing the name, and when it pops up in the list you click and drag it onto the desktop. You can also right click it and hit "send to desktop (create shortcut)."
Windows 10 can't do either of those things. If you try to click and drag a Start menu search result it does nothing. Right clicking only gives you the option to add it to the start menu or task bar. So, if you want a desktop shortcut, you have to add it to the start menu, drag it off the start menu onto the desktop, and then delete it off the start menu.
I experienced this problem as well, and is very disheartening. So many basic operations from good Windows version are either missing or very hard to discover on Windows 10. There was absolutely no _good_ thought put into its UI choices.
Being able to copy paste from the console. SMB3 (i.e. offering encryption if properly configured). Virtualization was a major leap forward in windows 8/windows server 2012. Http2 support in IIS.