Windows 10 is good, but what matters more to me is that my system fully supports it. Since Intel will never bother to write Windows 10 graphic drivers for my Sandy Bridge processor, the free upgrade makes no sense. Microsoft said my system was ready for Windows 10, but it turned out to be the opposite. I think Microsoft shouldn't have forced people with incompatible hardware like me to upgrade to Windows 10.
P.S Those who have Sandy Bridge processors just need to play an .mkv video on Windows 10 to see how incompatible their systems are.