I have come to the same conclusion you did.
Office 2013 definitely shows a marked improvement with Windows 8.1. They are still using the greyscale antialiasing and it still does not look quite as sharp as Office 2010. However, it is indeed much better and certainly usable now. The metro apps and IE11 also look much better. Not sure what they did to make it look better but I think you all will be pleasantly surprised. I'll be interested to see if anyone else notices an improvement with Windows 8.1.