The glass style for iOS app icons is completely idiotic. It's optional though. It doesn't even look good, it just makes the home screen look a little less crowded, but the UX is horrible.

Especially widgets are really bad. The widget for my car shows the battery level as a bar chart. During charging it's green, if there is a charging error it's red, when parked it's white/gray. In the glass mode I need to look really hard to see what's happening. All the color coded information is gone. Same for my todo list widget, due items are orange, long overdue items are red. With glass mode on they all look the same.