Although I never used it I do find the metro UI to be beautifully designed and intriguing, I would like to give it a try someday. I can't say anything about it's usability though, as I have read my fair share of bad feedback about it's problems, and I do find Microsoft's attempt to convert the "sacred" desktop environment into another mobile tablet friendly experience a bad move for the desktop oriented productivity users.

If I ever made a platform jump it would definitely be for the Linux environment and a more "open" ecosystem. But as I stand currently I rely too much on Windows, as it is used at work and by most other people, and the convenience of having portable apps in my thumdrive is just too big to drop for now :)