I love the light on the controller 
Not actually sure why.. i think its just because it looks cool. I hope they keep the light bar going forward. I gives the controller a very futuristic look..and it goes very well with the lights and pulsing of the PS4 console...again very futuristic looking...it kinda makes the ps4 feel "alive".
My only concern is the effect the light has on the longevity of the battery. Which really doesn't last long at all.
Edit: The speaker for example has a MAJOR impact on the battery.







