This glass broke on my fourth use, from it's own ice cube, with a reasonable amount of care taken.
The bottom peak of the glass is strong enough to withstand the gravity of the spherical ice falling from below rim height. But because the design automatically pushes the ice to the wall of the glass, the wall is not strong enough to withstand the strike from the ball rolling off the centre peak.
It might be less of a problem with the shorter glass heights. But for this one the only safe way to add the ice sphere seems to be placing it in horizontally, meaning ice first, liquid second always.
A slight change in design allowing the sphere to rest on the centre peak before tipping it into the liquid, could increase the longevity quite a bit.
The ice mold itself is all right, but nearly impossible to avoid a seam swelling around the middle during freezing. If you want the ice as clear as possible, the water needs to be very hot when it goes in the freezer.