Here's a short blurb from the post since trying to summarize this would be pretty pointless: You're going to want to read the original.
The post covers some excellent topics including the difference and relation between the Metro Design Principles and the Metro Design Language, fierce reduction, content not chrome, typography, motion, authentically digital, and more. Folks, this is the stuff that really sets apart Windows Phone from the competition, and I'm not sure I've ever seen it so succinctly explained. I can't wait to read the rest of the posts. In fact, I'll just read the rest of the blog while I wait. Good stuff.We usually refer to "Metro" as the UI design style Microsoft is using in their platform and the one Microsoft is exposing for developers and designers to create apps for Windows Phone (I'm focusing on Windows Phone in this series). But let’s delve a bit deeper into the term "Metro" and explore what it really means. To begin with, Metro is defined by two things: Metro Design Principles and Metro Design Language.The Metro Design Principles are the pillars (usually abstract concepts) that guide the creation of experiences for Windows Phone.The Metro Design Language is a set of concrete user interaction, visual design, motion and application flow elements and rules.