Indeed, the only argument against Windows 8 was that perhaps it was a bit too radical for the large masses of people who absolutely do not like change, but on the other hand, the same people seem to have no problem with other tablet operating systems which should pose at least as great of a change in the interface.
Anyway, as I work in healthcare, I have had the dubious pleasure to use Windows XP at work for the last few years. We just got upgraded to Windows 7 for most of the computers which is a clear improvement. There is much basic functionality missing in XP which makes it frustrating to use and it feels ancient in the design. Things like automatic search when pushing the windows button or resizing windows with shortcuts are missing in XP. Even WIndows 7 feels a bit dated though compared to Windows 8,1 which simply is a better OS than Windows 7 in almost every aspect except for the new interface if you really can't adapt. The start menu_ Well, seriously, for most people who can actually use a computer, the new menu in the left bottom corner is better, as you shouldn't launch frequently used programs anyway by navigating the old start menu.