There's change for change's sake, however. I reckon if Microsoft/Apple/Linux peeps produced the perfect desktop interface then they would have to destroy it to make people think what they get next is 'new'. People tend not to look under the hood - Win7 was a vast improvement on thread handling etc. than XP and so ran faster on similar hardware.
The metro interface, however, is a kludge by the marketing department in an effort to make WinPho8/X-Box and Windows look the same. It may be OK, good even (on a phone), when you have touch interface, poor otherwise.
Its obvious - your context keeps changing. I need to start 'word' so I go to the horrible metro interface, find the tile with 'word' on it (note, not a folder-tile that is called 'productivity') and click on it. Then afterwards I want excel. So drop out of the desktop and into the metro interface, find excel then start it up... to drop me back into the desktop interface. This shouldn't be necessary, and you shouldn't have to pin a load of binaries to your task bar either.
I'm all up for new interfaces but with a history of what works it should be evolutionary, not like this. There are better ways.