Valve Confirms May 4 Steam Controller Launch Ahead of Steam Machine

The back of the controller features 4 buttons and Grip Sense sensors, as well as a magnetic charging latch for the Steam Controller Puck.
The new Steam Controller essentially takes the Steam Deck controller layout and converts it into a traditional gamepad form factor. The trackpads, touch-sensitive analogs, and gyro are all present, as well as improved, drift-proof TMR thumbsticks and additional "Grip Sense" sensors on both handles.

Valve encourages "ratcheting" the gyro toggle with the Grip Sense areas.
Valve's official announcement describes Grip Sense as a "new input that uses capacitive touch sensors to sense if you're holding the handles". It's intended as another way to toggle the gyro feature, but Valve also points out that Grip Sense can be mapped for other buttons. It can even be used to pause a game when setting the controller down.
Early impressions of the controller are positive, and indicate that the D-Pad, buttons, and triggers all feel about the same as on Deck. The sticks seem to offer an improved feel and should be more durable thanks to TMR sensors, and Grip Sense seems like and interesting addition.
Hopefully, we get our hands on a unit sooner rather than later, and will post our first-hand impressions.