The biggest addition is the all-new Share Button, which allows you to broadcast recorded video to friends via the Internet, social networking, your PSN list, uStream, etc.
The other biggest change in terms of input is the all-new Touch Pad. The Touch Pad on the PS4 controller will improve playability and allow for new experiences similar to that of a touch-screen (although not as diverse naturally) or the touchpad on the back of the PS Vita. In addition to being able to interact by touching or moving your finger across the touchpad, you can also click the TouchPad in, adding another button to the controller.
Other changes include a built-in Headphone Jack so you can play using headphones quickly and easily right from your controller (AWESOME NEWS! Why hasn’t anyone thought of this before?), the jack also allows you to plug a headset in for voicechat. A built-in Mono speaker is also included just like on the Wii.
Another major new feature is the Light Bar, this will light up to indicate what controller port you are plugged into (just like on the Xbox 360) but can also be used for gameplay such as to indicate low health levels, via different colored lights on the controller.
Additionally, the Light Bar can be sensed via the PlayStation Eye peripheral that comes with every PS4. And the PS Eye can track your movement using the Dual Shock 4’s Light Bar, which will work very similar to the PlayStation Move Controllers.
Other changes for the PS4 controller include: An “Options” Button finally replaces the Select and Start buttons that have existed since the original PS1 controller, and going back to the original NES/Famicon in 1983/84/85; a Micro USB port will be included much like the PS3 controller, you can use it to charge the controller (which can also be charged via a charging station or via the console, even while off); an extension port; rubber or etched plastic backing to enhance grip, Motion Control via a three-axis gyroscope and three-axis accelerometer, and improved rumble capability.
Besides the new features, the Dual Shock 4 will include all the features you expect from past PlayStation controllers: Four face-buttons (X, Circle, Triangle and Square), four shoulder buttons (L1, L2, R1, R2), Two Control Sticks (that are now concave with a hole in the center like the Xbox 360), A D-Pad (using the familiar cross unconnected cross shape) and clickable Control Sticks that represent the L3 and R3 buttons. The speaker is in the middle of the controller, with the Share Button on the upper left-hand side and the Options button on the upper-right hand side. The Touchpad is in the upper center of the controller, nearly the length of it from the end of the D-Pad to the Face Buttons.
Last but not least, the PlayStation Button (or “Home” Button as it’s called on Xbox 360) is in the center of the controller, to bring up the Main Menu, PlayStation Network, access your friends list, etc.
The Light Bar is on the top of the controller between the shoulder buttons (along with the Micro USB slot) while the Headphone jack is presumably on the bottom of the controller, where the headset jack on the Xbox 360 is.
All in all I am very pleased with the PS4 Controller and the Dual Shock 4 looks like a great upgrade to the Dual Shock 3. Speaking of which, it’s worth noting that the Dual Shock 3 Controller will NOT work with the PS4… The PS Move Controllers are supported however.