I am stunned so many windows users are failing to spot the huge number of differences. Button stylings, hover highlights, rounded corners on cells, scrollbars, group box backgrounds, menus, checkboxes... Maybe as a developer my eye is tuned to look for such things, the differences are considerable that hit me immediately. Then again I did lose most of last weekend helping Kovid test getting buttons the same height so maybe I've spent too many hours looking closely at it already...
My vote is for it to be the new default style, for the most part the changes are good and since a Qt based app never looks like a standard windows app anyways you may as well go the whole hog and make it look prettier. Kovid knows the one thing I don't like about the new style but if others don't spot it and comment on it I'm not going to fan the flames by mentioning it since he likes it as is