Pros : very solid and each one is very heavy. It has a pro finish look, you could even apply cabochons to the covers
Cons : The slot is SO wide you have to have a high degree of curvature or quad thick glass to be able to actually secure it, the adjustable screw adjusts about 1 mm so it's use is negligable.
First installation is not straight forward, there are no directions or instructions and you can't tighten the screw holding the device to the wall once the art work is in it, so getting the art in place is a magic trick. And it will never be secure. There's no rating to know how much it can hold, and honestly, they are heavy enough in their own right there is no using brads- it requires studs.
Then once you install one and put on the cover, there's no changing it, EVER. The cover is counter sunk and applied with adhesive so removing it to change or even release the artwork it's holding is difficult and not always safe. On top of that, you'll have trouble getting the cover back on if you are trying to leave them in place to change or even just thoroughly clean the art work.
Other Thoughts : They are sold individually, which is nice if you say only want 3, but 1 is NOT enough to hold a piece, so make sure you order enough, and realize that hanging your art work will cost at least double, and probably 4 times the price listed.