Video and audio are working. Mouse is implemented with support for the touchscreen as a touchpad or using a real mouse or touchpad. Keyboard support is also implemented. Pressing back/select and start together on your controller will bring up the Steam overlay.
General requirements for current APK:
Android 4.1 or higher
GeForce Experience with a GTX 600/700/800 GPU (or other GameStream compatible configuration)
Steam enrolled in beta updates
Xbox, PS3 (with SixAxis app), PS4, Moga Pro (HID mode), Shield, or Ouya controller (other controllers may work too in HID mode)
Mid to high-end wireless router (preferably dual-band 802.11n or better)
Good wireless connection to your Android device
Changes:
Add support for the PS4 controller
Fix a bug that would cause the video stream to fail to start on some devices