I installed it... and removed it two hours later. Anything worth doing in Windows 8 dumps you back to the desktop. Example, you want to use the Music app with your already existing library but it isn't installed in the standard library location. You have to use Windows Explorer, which also requires you go back to the desktop, to designate the location as part of your library. Let's say it mislabels an album, say a punk rock album gets album art and stats of a similarly titled gospel band, you cannot update it from Metro or the music app. Same thing with IE 10, no bookmarks in Metro, everything gets dumped to the start screen, so good luck finding much if you have more than a few links. You can still get the good 'ol favorites back by going to the desktop.
My question is this: If all I'm doing is sitting on the desktop to do work, why bother with Metro at all?