Buttons are still in high demand, just ask Valve.
On the first day of Valve’s Steam Dev Days event in Seattle, developers revealed the new design of the Steam Machines controller. The most noticeable difference was the absence of the central touchpad, which is now replaced by two sets of physical buttons. Valve said this will help with backwards compatibility. During a demonstration a few months ago, the controller performed quite well with the touch pads, however it seems consumer feedback, and backwards compatibility issues have proven otherwise.
The controller will use two AA batteries, and with the new set of buttons, it bears a striking resemblance to Nintendo's Wii U controller.
Valve explained that the company is still in the middle of processing beta feedback, so you can expect more changes to the controller. After day one of the event, many in attendance received a gigabyte Steam Machine, along with the first iteration of the Steam Controller.