I've used one.
Vision is good in them, they are lighter and less cumbersome than a helmet. Much more preferable on hot days!
Ball doesn't hurt if it hits the face mask at level I play.
The padding on them is quite hard though and presses against your face.
Totally agree with this.
I've used one for the past 3 years for at least 2/3 games a week.
I think they're awesome but as mentioned, they do press against your face.
They do soften after a bit of use but I still seriously rate them.
I have the titanium P1 mask and it is so so light, much better than a helmet on a sunny day