Mixed results for me. Some games require some tweaking, others don't work at all. Mostly older stuff. Windows 7 had better compatibility from my experience. Unreal Engine 2 games don't like running full-screen in Windows 10 (heard it's the same with Win 8) unless you can get hold of a 64-bit version, and aside from UT2004 I haven't found an Unreal Engine 2 game that does. Sam and Max Seasons 1 & 2 just won't run, nor will the original GTA, just for two examples.
That said, with Windows 10 I could run Middle-Earth: Shadow of Mordor with the optional Ultra-High Res texture pack better, which recommends a 6GB or higher GPU (mine is 4GB). On Windows 7 if I tried it I'd get framerate drops if 8-10 enemies or more started attacking me. In...