A few years back I fumbled my iPhone so badly that when I tried to catch it I knocked it further up in the air. It flew up dropped all the way down to the concrete subway platform I was on, landing face down. It was loud and worrisome, but the phone was perfectly fine outside of some scratches on the lip of aluminum around the screen.

So it seems like the screens are not easily broken anymore. Though that event did lead to me using a case on my next phone just to avoid chancing cosmetic damage on it.