If you want to know why we needed a new interface concept then Microsoft did the worst compared to competitors.

Google was really innovative and has made a very usable new interface, within Chrome and Android OS (Apple also did a good thing on iPhones and now on its iPad tablets).

Microsoft is late in everything, and first in the usability. The excellent tiled interface is the one you find on Android OS and on the Chrome applications store. Even Firefox has a much better interface for its application store (replacing now the former selector for themes and addons).

The Google experience is not only usable, it is excellent across platforms from the smallest smartphones via the tablet to the desktop and notebook or even on your TV. Everything is synchronized (including third-party applications, with the new NaCl, acronym for the Native Client library, and for its builtin virtual machine which provides a secure sandbox). If something crashes on your PC, just drop everything and reinstall the browser : everything will be instantly resynchronized. There's nothing as simple to use as Google applications and its third party providers. Intuitively, even if there are dramatic innovations in the UI.