Invisible shield vs screen protector that comes with the phone

Does anybody know if the invisible shield by Zagg, is significantly superior tothe screen protector that comes with the phone?  I bought my phone from Best Buy, and the salesman recommended the that I buy the invisible shield, (before I knew that it already came with a screen protector in the box). I already applied the one that came in the box, and currently contemplating whether it is worth removing the screen protector the phone came with and reapplying the invisible shield instead - or should I just return it and get my money back.  I already have a case for the phone and use a belt clip, so I am only concerned about the front screen.  Thanks for any responses    

Having tried both, I can honestly say the 20 bucks is worth it ...The invisable Shield has a nice feel to it when using the stilus...a more precise feel whereas the screen protector in the box has a cheap slippery feel.