Metro Modern UI has a-lot of potential. Windows Phone is a good example of it. As an OS, it is brilliant with some minor perks here and there, but that's just how OS companies roll, not adding all functionality in one swing to maintain the update credibility adding stuff update by update. Trust me, future updates will bring WP functionality on par with Android and iOS. The app situation also needs time. Microsoft will leave no stone unturned to bring all the major apps to the ecosystem, no second thoughts about that.
"Live tiles are awesome". This statement has both subjective and objective elements to it. People might argue that they are not as functional as widgets on Android, might be true( never had an android device) but they are definitely more pleasant looking and aesthetically intriguing. Neat, sober and pretty functional.
Windows 8 is a different story. Metro interface is the most superficial aspect of Windows 8, and consequently more noticeable. However, there is a big gap between the metro and desktop part of the OS. it is like time travelling. The metro parts look so 2013, and desktop so 2008. It is not a bad thing to carry forward good things from the past to the future but connecting them with present and future elements can be daunting. This is what Microsoft need to do. Windows Phone is a great uniform OS, people who say otherwise have their heads in iOS and Android sands. If somehow Microsoft can make their modern UI uniform throughout Windows 8 without axing off the traditional windows functionality and elasticity ( same applies for windows RT), i bet you my kidney that Microsoft can and will beat the shit out of Google and Apple in months.