At the last Melbourne XDDN meeting, Shane Morris (@ShaneMo) did a great session on “How to be authentically digital”. In it he covered off what the Microsoft Metro design language is and what the principals of it are. He gave a great insight into how the Metro design language pulled in influences from a number of design styes, such as Bauhouse and motion design.
Shane talks about how using the content itself to provide form and structure to the content can be combined with typography hierarchy. He gives examples using his own applications and shows that not all Metro designed applications need to look the same. There is a lot of room for personalisation as long as you keep the core principals in mind.
I highly recommend watching his session if you have the time.