Peter Bright for Ars Technica:

These are not touch applications, and you will not want to use them on touch systems. They’re designed for mice and they’re designed for keyboards, and making the buttons on the ribbon larger does nothing to change that fundamental fact.

This is exactly what I’ve said all along. Desktop apps do not transition to a touch-enabled environment very well at all. No matter how much Microsoft wants it to work, it’s not going to happen. This is why Apple developed touch-enabled versions of Keynote, Numbers and Pages.