For starters, it needs to work out of the box with the average user in mind. I don't think I've ever had a smooth install that didn't require searching the Ubuntu forums to get basic stuff running. If Ubuntu wants to compete with Windows, it can't ship an operating system that can't wake from a suspend on most laptops and requires using a terminal (which most people don't even know what it's for) to perform basic tasks and configuration. The experience for a novice computer user, however terrible you think Microsoft is, has always been excellent on Windows in that it suits their needs of requiring only little knowledge of how software works.