Recs.
Updated
The Steam Controller is a controller for video games developed by Valve that is designed to work well with PC centric games that normally would only work well with mouse and keyboard controls.
SpecsUpdate
Pros
Pro Developed specifically for PC games
The trackpads built into the controller make it simple to play certain games that would otherwise be impossible with a controller, such as Civilization and Cities: Skylines.
Pro Integrates well with Steam
Considering this is a controller designed by Valve, it should come as no surprise that the integration with Steam is quite good. The user can easily launch into Big Picture mode straight from the controller for ease of use. The controller is plug and play, so there is little to mess around with in order to get going. For those that would like to customize the button layout, Steam allows for this in their settings.
Cons
Con Feels cheap
The controller does not have much weight or heft to it and the entire things is made out of light plastic giving it a cheap feel, something akin to a $20 controller for one Android or iOS device. The face buttons on the device are also small, with the shoulder buttons feeling stiff. Overall the lack of attention to detail with the buttons and the overall feel of cheap material gives a sense that this is not the most well designed or thought out controller on the market.
Con Not as accurate as keyboard and mouse
The touchpads on the device are designed to emulate a mouse when playing games, but they are not as accurate and will at times require a lot of swipes in order to just turn a character around or even just look around. This lack of accuracy and delay in how long it takes to get the movement required may be difficult to get used to.