I love using mirrors especially in small or close areas. Because they reflect light, they can actually make a room brighter. Brighter rooms appear larger then they really are.
Placing long wall mirrors in a hallway or small area can add a sense of width and depth , making the room appear larger. While part of this has to do with light, it also has to do with how the eye perceives the space when colors are reflected. Because of this color reflection, there is more for the eye to observe, which tricks your brain into thinking the space is larger.