Some are working better and some never-worked-before games are working on Win10. I think they added some features that helped with backward compatibility.
That said, some don't work anymore (especially as above noted, the DRMed up games).
I've been using Win10 since just after it came out. Overall, I've been displeased -- mostly due to the default settings (most annoying: it reboots your computer without asking after downloading an update -- you can turn that off, though). A lot of the features are fairly useless.
My system boots a lot faster, but then I'm forced to download updates (there is no turning that off if you're on a wired connection). So sometimes I have to wait up to an hour to be able to actually use my PC for any games that take more power than solitaire (which now includes ads).
If you have children and you want them to have a child's account, you have to pay 50 cents per child to prove you're an adult and not a child. (I still don't understand that)
For me, I'll keep using it for now. I don't have the time to fiddle around for now, but when I do,I'll be putting Linux on as a dual-boot system. I don't want to give up on Windows yet. I'm hoping they'll fix these major issues and give us control of our PCs again.