Beyond the cold shower curtain argument and the decor enhancement customizations, glass shower and bathtub doors have the luxury of being easy to clean.
Shower curtains are made of an outer, thinner vinyl sheet, and a thicker, inner sheet, designed to be pretty on the outside, and functional on the inside. The problem with this bi-partisan concept, is it's hard to clean both thoroughly. If regular cleaning isn't done, just like dirty shower tiles, mildew will form and make the curtain smell.
Glass shower and bathtub doors on the other hand are easy to clean, and there's even an attachment that can connect to your shower head, that sprays a cleaning agent on the shower's interior, including the doors, on programmable intervals If you do not possess this neat little tool, some antibacterial window cleaner and a soft, scour pad will clean the door and get those hard to reach areas near the frame, if there is a frame. Then, just wipe it down with a paper towel.