Are glass screen protectors for my iPhone a good invesment?

Http://www.spigen.com/cell-phone/apple-iphone/iphone-5/iphone-5-screen-protector-glas-tr-premium-tempered-glass-series.html

I've come across these "glass" screen protectors and are wondering if they are a good investment. I have a plastic one but its has started peeling on the edges. Are glass screen protectors really better and worth the higher price or is it just a marketing scam?

They likely would cause major problems with accessing the touchscreen on the phone, and I wouldn't recommend one.