i admit i don't use them all the time and i should. i do use them often though. to think that your eyeglasses will protect you forever is pretty naive, especially if you're using a demo saw, grinder or similar tool. those tiny bits of metal fly everywhere and can easily make their way past safety glasses. if you're cutting or grinding with one of those tools you really should have glasses and a shield. i realize most places (under houses, tight spots, etc.) don't really allow this.
say i'm cutting out some rotten cast below a house and i can't use my snap cutters. if i've got the grinder or sawzall out i'll be wearing one of these.
i really like it. very comfortable, all things considered. doesn't fog up. keeps the stuff out of your eyes AND out of your lungs. i think this is my best safety purchase. highly recommended.
paul