Too large size will make some problems with cleaning and so on. Also if you look bad in the morning then do not put on the looking-glass against to bed.
Some interiors are perfect to be decorated by mirrors. For instance, large wall round mirror will look great in a hallway or narrow corridor. Such a method will brighten up the area by making it wider and bigger. Sure, various kinds of mirrors must be applied for different spaces. Take into account, a large looking-glass is like a masterpiece.