I have a moto razr 40 at the moment, the crease is pretty good. Depending on the angle it will show with a dark background and when the screen is off. On a lighter/white background the crease is not visible. It’s also less noticeable to the touch than any other flip smartphone. I can’t comment too much on durability since most common issues are going to show up after years, not months, but I think overall the industry is making progress with regards to hinge and display design. The current generation all fold flat now and have a different hinge structure. As I understand it flip smartphones are selling well so hopefully that means they keep working on the technology and improving it.