I would never attempt to install one of these myself. That's why I spent the extra to let BB install it. The guy that did my first GN/2014 (16GB version) applied it in one try. Perfect! I don't see any difference with or without it. There is a slightly different feel but for MY needs, it's not a problem at all. The guy who put the Zagg screen protector on my 32GB GN/2014 wasn't as good. He had to open another screen protector before he got it right. The store eats the loss, not me and if the install goes bad, ever, they replace it.
Maybe if I had two screens in front of me, one with and one without the protector, I could tell a difference. If I try really hard and get just the right angle in just the right light and look hard, I can see the protector. Other than that, I can't tell it's there.