From the article I read, there are like ten different interpretations about WinFS. Some consider object oriented FS, some say it is relation database FS, some say it is XML database, and more. No one can really clearly say what it is. Or a better way to put is, everyone focused on their own implementation aspect of it, but, the technology from an use case point of view, is lacking. No one can't exactly say why we want it and how it can be better. And most of all, it is a research FS too early to be used widely.