Metro is Microsoft's future. It's going to be the base for the UI of the next Xbox (it's already in the current OS). It's the basis for Windows 8 as we all know and it's been the basis for Windows Phone ever since WP7. While getting mixed reactions from some of the public, it's still what Microsoft believes in and will continue to implement because Metro is based off of years of R&D so to throw it away would be a loss. We'll be able to see how the public feels about it come Christmas season. Windows 8 goes on sale October 26th.
I think it's only decent when it's on a tablet. Desktops would just be useless, I mean clicking big squares? Kinda inconvenient really. And it's still just really bland.
I have a Windows Phone 7 and I love it. It's simple, neat, beautiful and elegant. It just looks so much nicer when seen on device than on these screenshots.