Just bought the #Steam controller and I am very impressed with everything other than the build quality; it just feels a little cheap for a $50 controller.
I plugged the wireless adaptor into a USB port, turned it on, and was prompted to quickly update the firmware. After that, there was a little tutorial that shows the basics. I tried it out with Borderlands 2 to find that the controller is officially supported and pre-configured; you could change that if you wanted but I found it perfect! 😁