Of my 100 something GOGs, only two don't work 100%. The rest either just worked, or worked with light/heavy tweaking.
And actually, the two that don't work seem to have frame rate issues, the frame rates are to high. I don't know for sure though, too lazy to do tests and try and fix it right now. :P
A number of games here need me to write a batch file, to kill explorer.exe, otherwise you get major discoloration. Then when I exit, it launches explorer.exe again.
And small number of games also need me to limit the amount of cores they use to prevent crashing.
So yeah, you might run into trouble, and every PC is different so something that worked for me might not work for you.
Also, I'm not completely knowledgeable on this subject, but I think virtualization won't support games running on Direct3D or OpenGL (Correct me if I'm wrong)