Tahoe is a bit shit, yes. But I was there for both Vista and Windows 8 and they were both utterly unusable.

Vista ate every bit of RAM it could find, had severe driver issues and riddled with instabilities. It would not run on half the hardware at the time. I faintly remember a DX10 shitshow as well. And 8 hopelessly tried to apply Metro to the desktop and added a third (or was it forth?) settings panel. Also killed the Start menu.