I upgraded from W7 to W10, and have been coping fairly well.
If the computer has W10 as an original installation, you won’t need to do things like upgrade and re-install printer drivers, etc. (I had to go through some song-and-dance to retain compatibility.)
The Windows File Explorer behaves a little differently. You’ll take a little time getting use to the new look-and-feel, but it isn’t anything I can really describe. Just mess with it till you get used to it.
(When I plug in a USB took, like my Kindle book-reader, my phone, or just a memory stick, two separate instances of the file-system come up. I have no idea why. But they both work, exactly the same, so I guess I don’t care. Just a weird little thing some knothead came up with.)
I re-installed the old version of the Windows Photo Viewer, and re-assigned it to be the default viewer when I double-click on a picture (jpg, bmp, tiff, etc.) file. The new version is clunky, and, worse, somehow got badly configured, so that double-clicking on a picture file automatically opened it in Paint, and I couldn’t turn that “feature” off again.
Seriously, there aren’t that many differences. Lots of people say they hate W10, but it “looks and feels” so much like W7 that moving up was very, very little hassle for me.
ETA: Yeah, the games seem to have gone away. But if you like killing time with solitaire games, take a peek at Edward Kaser Software. The guy designs and programs his own solitaire time-wasters, and I am a big fan of them. “Mrs. Hudson” and “Watson’s Map” are my faves.