What's wrong with the GUI?
It's virtually identical to Windows 10 and the smart tiles are off by default on Enterprise (business) versions of Windows. On home versions you just drag left to permanently collapse the smart tiles on the Start Menu.
Here's what the typical Windows 10 business GUI looks like:
https://pbs.twimg.com/media/CNH5IT3XAAA988I.png
I'm not saying Windows 10 is perfect but there's nothing wrong with the GUI in my opinion.