Update (2019-11-28 15:00):
The Steam Controller launched back in November 2015, a little over 4 years ago today. Alongside the Steam Link and Steam Machines, it was part of Valve's plan to get Steam into the living room. Steam Machines were unfortunately, pretty much dead on arrival. However, Steam Link did gain some traction before being discontinued about a year ago today. The Controller was probably the most successful of the three products and managed to get a decent following.
After the Steam Autumn sale began yesterday, Valve seemed to be unloading their remaining Steam Controller stock by discounting the item by 90%. Including shipping, that worked out to about 13€ here in Germany. At the time of writing, less than 24 hours after the start of the sale, the Steam Controller is now sold out.
People seemed to have a love-hate relationship with the Steam Controller. My personal experience was that it worked amazingly in some situations, especially when games had native support or only support mouse and keyboard. In other situations it just didn't feel right, like when forced to use the trackpad as a virtual joystick. In terms of Linux compatibility though, it was fantastic when used through Steam and quickly became my go-to controller on PC.
So is this the end for the Steam Controller? Maybe not. In July of this year some keen-eyed observers noticed a patent application and some Steam Input variables that point towards a version 2. Valve hasn't said anything about this though so all we can do is wait.
Have you ever owned or used a Steam Controller? Let us know your experience in the comments.