The flat "metro" style that Zune/Windows Phone have is best when it's clear that it's a UI you're meant to interact with. There's no need to show button-like things on a list that says "music phone contacts" - the fact you're in a touch UI means its obvious you're going to touch stuff.
For non-touch and complicated UIs, it's a lot less useful. See Office 2013's mess of a UI, which also added ALL CAPS as a design element that literally conveys zero information (there's no common trait caps has across the applications, it's purely a random design change for the sake of some really poor design sensibilities).
For non-touch and complicated UIs, it's a lot less useful. See Office 2013's mess of a UI, which also added ALL CAPS as a design element that literally conveys zero information (there's no common trait caps has across the applications, it's purely a random design change for the sake of some really poor design sensibilities).