Very solid (it's metal). The downside is that the lenses are not covered and are exposed to hits from sharp surfaces. They have done half the job...

It protects the area around the cameras. It is slightly taller than the lenses but anyway the case is higher than the lenses. If the phone falls on a pebble, one pointed surface, the cameras are not protected at all. It protects the flash and the other 2 sensors to a great extent because they are deeper. The only thing that may be affected is the flash, I have the impression that it does not allow the light to be evenly distributed in the space like in my previous iPhone where I did not have this specific protector. However, I am not completely sure since I have not tested the flash without the protector as I put it on as soon as I received the phone.