It looks like the Valve Steam Controller BETA is proving to be effective, there is already a major design change in the works that will remove the touchscreen faces, and has reverted back to buttons. The touch-face design is what gave the Steam Controller its unique look and we are somewhat sad to see them leave, but apparently they are not up to Valve testing standards at this time.
The new prototype, shown at the Steam Dev Days today, adds some standard button placement to the controller in lieu of the touch-face. Also removed are the A, B, X and Y buttons that were located at the corners of the touchscreen. GameDeveloper Tomas Rawlings of Auroch Digital posted this image below from the event earlier today:

The controller is sure to undergo more changes as the BETA continues, we will keep you updated on Valve’s process as the weeks pass on.