Yeh - killer features are a big bonus. Thing is they are cool to work on - and so quite a few seem to work appear, pulling people in. With OSX and Windows that's fine because IMO they have that extra level of ease and Usability that a consumer OS needs. Linux doesn't have that left - I bet a lot of people drawn in with a gimmick are left struggling with it after a few weeks...

I still maintain that Linux is lacking a simple UI to pull it into the mainstream (ALL Linux not just Ubuntu).