I thought the toughened glass screen was very durable. Much better than plastic screens on other phones.
Not at all. It's not tempered glass. Tempered glass shatters into little pieces.
This is what Apple says is "optical quality" glass. Not sure what that means, except perhaps it doesn't have waves in it.
Nowhere near as tough to break as plastic, but they switched to glass at the last minute because everyone was complaining that plastic would get scratched up easier.