Most notable bit is CMD supports long paths now. You still need to enable the long path policy as it isn't on by default.
.NET 4.7 had some minor tweaks. It now allows using device syntax (\\?\) with FileIOPermissions as long as you are running in full trust. This should allow you to use \\?\ paths everywhere (classes that asserted permissions outside of mscorlib didn't work in 4.6.2).
I also fixed a bug on my part in 4.7. (doh)