I bought a new computer in August and waited to pick it up in September, so they computer store (custom build) could install a clean copy of Windows 10 instead of doing an upgrade. My son upgraded his laptop from Windows 8 to 10.
I have not problems at all with the interface. I have been using Windows since it first came out and generally there is a period of adjusting. I have used different versions of Windows on different computers the same day at work and it is not hard to go back and forth between OS on the different computers.
I do have an issue that when I use Internet Explorer on this site and this site alone, that my key strokes do not register properly and I have to back up and retype repeatedly. I have brought this to the admins attention, but got no reply. They will have to upgrade the code in the site sooner than later.