As far as I can see, from various reviews on the web, all the 'improvements' appear to be cosmetic. I did try downloading the insider preview on an old PC, which aborted after a few minutes and reverted back to the installed Windows 10 build, telling me to reboot the system. It then immediately repeated the 'upgrade' process which aborted again
so I have abandoned the insider programme which I joined for the Windows 10 previews. I think I can wait a few years until I'm forced to upgrade, by which time I'll probably need a new PC anyway . . . if I'm still capable of using one by then