How many times have your fingers slipped off the L2 and R2 buttons of your Sony PS3 Controller and always at the crutial moment in the game. Real triggers put a stop to that happening ever again. Simply put if you use a Sony PS3 Controller and serious about your gaming you should use these.
They slide/clip on to the convex triggers and add a concave curve, helping your fingers stay securely on the trigger buttons [people were complaining that their fingers would slip off]
Other than adding security for your fingers, that´s about it. If you want to revert back to the old triggers´ feel, removing the clip on triggers couldn´t be easier.