This lightswitch in my room has a good design. It is easy to use and has a very conprehensible signifier: it is a lever, so it goes up or down. Easy to use, easy to understand. It also helps that this image of a light switch is very recognizable. The light that it controls is located very close to it. Thus, it is very obvious which light source it controls (the other light and its corresponding switch are across the room and further apart from each other compared to this pair).
It is very useful, as it is located right above my bed, so I can turn it off from the comfort of my bed and go directly to sleep instead of fumbling my way across the room in the dark. It does not obstruct anything else in my room and is not ugly (I like the round light, it has character). It does exactly what it needs to and you really can’t mess up while using it. Being by my bed means I can do some late night reading snuggled under my covers.