In our preview of Office 2013, we couldn't help but point out that the new Touch Mode was a "clunky" and still primarily optimized for mouse and keyboard. Nevertheless, Microsoft did make some changes to the core apps to make them more touch-friendly, creating larger targets in the ribbon and elsewhere. A new blog post from the company details many of the changes and the reasoning behind them — including the aforementioned ribbon changes, text selection, and app behavior when the keyboard is visible. That last was particularly tricky, as the on-screen keyboard takes up quite a bit of screen real estate and so the ribbon and other on-screen elements needed to be re-thought for that context.
Nevertheless, for all the thought that went into the main Office 2013 touch interface, it's not all that different from the standard look and feel. The same can't be said of the completely re-thought OneNote and Lync apps, which have been done up in the Metro style and include a new radial menu. Microsoft details some of the design decisions there as well — decisions we wouldn't mind seeing applied to Outlook, Word, Excel, and Powerpoint someday.