Comment 1 for bug 1372555

Ondrej, System Settings runs in landscape mode because it's useful -- for example, if you need to change some settings while watching a video -- and there's no reason to prevent it.

Can you be specific about it being "not pretty"? It's true that it wastes a lot of space in landscape mode, but it wastes a lot of space in portrait mode too; that's a toolkit problem, not specific to System Settings.