You mostly use a pinhole camera to become familiar with the basic elements of photography. Plus it is an interesting and different way to take pictures. A smaller pinhole will give you a better picture. Although an extremely small hole will cause too much diffraction and make the picture not as clear. Pinhole cameras give you continual depth sharpness, compression of time, a very wide angle of takes, exact prospective projection, and visable and not visable (to the human eye) light spectrums (
http://www.pinhole.org/).