I brought one and installed it just now. I had the Carez HD Clear plastic protector on - perfectly - so I was reluctant to change it so soon .....
This glass protector covers the screen if you get it 100% precise. It is exactly (exactly!) the width of the viewable screen. Mines almost 100% precise, just slightly off near the touch id. There is no front camera cut out.
As the protector has rounded edges and it only covers the exact screen when viewing from an angle you can see the screen 'under' the protector. No big deal to me. Front on view is fine. Its all securely stuck down.
I got acouple of tiny bits of dust under but you can't see them when the device is on. If something better comes out ill change it.
Feels smoother to touch than the plastic protector and probably better screen view - as expected from previous experience with glass protectors.
----
UPDATE : It needs to be a slightly wider 0.5mm on each side. Sitting in a dark area i can see the protector on the ever so slightly off centre placement side from the front view.... hmmmm ... wish id got it precise.
Some pics. Keep in mind my alignment is out by (I'm guessing) 0.1-0.25mm on the side I'm showing. If it was PERFECTLY fitted you prob wouldn't notice as much. I don't see it on the other side but that is ever so slightly over. From the front you don't know any different. Either way they should add 0.5mm to each side.