Excellent case given it is specifically designed for storing the Steam Controller. The controller fits snugly inside with room for the USB dongle and base underneath. The case itself is a "hard" shell that will stand up to normal storage impacts and pressures. You won't be able to put significant weight on top of it, but who would do that anyway. The material used is easy to grab and should keep the controller dry as well. Zipper is of good quality as well.
Just like the alternate battery door, this should have been included in the price of the original controller to add purchase value of Steam's hardware. Now they've discontinued and everyone is pissed. Valve disappoints again.