When I upgraded mine I ended up with a hybrid of W7 & W10, some parts of windows had the new look & some parts old. I had already backed up everything I wanted, so wiped the hard drive with boot n nuke, did the clean install & now all is almost well. I didn't even bother to test it for a few days after seeing the hybrid hotch potch mess I ended up with.
I have noticed excel 2010 now crashes regularly when saving. It "So Far" seems to be related to the printer driver (Canon) the same printer driver that gave no trouble with W7, there is no W10 driver. It's now set on the Canon XPS driver as default & hasn't crashed yet, it still crashed on the MS XPS driver