Years 2011 and 2012 brought, and will bring, significant changes to all of these operating systems. Maybe not on the core level, but certainly on the user interface level. Unity, GNOME3, and now Windows 8 user interface styles are... I won’t say they are bad or wrong. I will say they are different.
Many people wrote on the Internet about their rants, excitement, pros and contras. I myself did not stand aside from that battle. I compared them both on early stages and running in the same Ubuntu system. But the war is far from being finished. It has just started. There will be more to come when the new Windows 8 eventually hits the shelves of computer stores. This wave promises to be much stronger than the Unity and GNOME3 ones.