Recs.
Updated
The Steam Controller is an innovative and unconventional controller. It's easy to set up, though a bit difficult to get used to. It has very customizeable button schemes.
SpecsUpdate
Pros
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.
Pro Fully configurable
The control scheme can be freely changed by the user. You can customize what each button and axis does in any specific game.
Key mapping is not limited in any way, so if you have unconventional preferences about what you wish to use some keys for, this controller will not stop you.
Configuration schemes can be saved as templates and then shared with the Steam community. This can sometimes save you the effort of mapping your own keys for every new game you play.
Pro Handles shooting games well
The Steam Controller beats most other controllers when it comes to shooting games. The aiming is rather precise and fast. Although it's still impossible to beat a player who uses a keyboard and a mouse, the controller works great for singleplayer shooting games.
You can also try aiming using the gyroscope. Though fun, the right trackpad will do a better job in practice.
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 Unconventional design
It may be hard for many users to get used to the layout of this controller. The buttons are unconventional and also differently positioned, compared to the regular layout of Xbox and Playstation controllers. In addition, the overall shape of the Steam controller may feel odd at first.