Rockstar and Sony have detailed some of the unique features that PlayStation 4 owners will get to experience in Grand Theft Auto V thanks to the DualShock 4 controller. Most notably, the touch pad will be put to the most use, but the light bar and speaker also adds some functionality.
Switch seamlessly between camera perspectives on the fly (including from first person to third person), switch radio stations, weapons and camera angles, and even quick-toss a grenade in the middle of a firefight – all with a swipe or a tap on the Touch Pad.

Because any aspiring career criminal would do well to keep their enemies close, you’ll be able to hear police radio chatter through the DUALSHOCK 4 controller’s speaker, as well as receive phone calls from friends and acquaintances Michael, Franklin and Trevor make during the course of the game.

The controller’s light bar will change colour based on the character you are playing and when the LSPD heat is upon you, the Light Bar will flash red and blue to make it perfectly clear that you might want to be somewhere else.

It's all completely unnecessary but it's neat that all of that is an option.