It appears that those lucky 300 beta testers have been quite busy as Valve has decided to drop the touchscreen on its Steam Controller and add a couple of new physical buttons.
According to some info coming from Valve's Steam Dev Days conference, it appears that the touchscreen could divert players attention from the screen so Valve has decided to get rid of it. Valve has also added a couple of new physical buttons to the Stema Controller, or to be precise, two clusters of four buttons placed in a standard button arrangement.
According to various tweets, Valve will include "ghosting" mode which should provide an on-screen visualization of the buttons. We will probabaly hear more quite soon and with the touchscreen out of the the controller picture, the final version of the Steam Controller should be at least cheaper to both produce and sell as it hits retail/e-tail later this year.