From Photo.net: "The classic technique for street photography consists of fitting a wide (20mm on a full-frame camera) or moderately wide-angle (35mm) lens to a camera, setting the ISO to a moderate high speed (400 or 800), and pre-focusing the lens. Pre-focusing? How do you know how far away your subject will be. It turns out that it doesn't matter. Wide angle lenses have good depth of field. If your subject is 10 feet away and the lens is set for 12 feet, you'd probably need to enlarge to 16x20" before noticing the error, assuming a typical aperture. This is why the high ISO setting is important. Given a fixed shutter speed, the higher the ISO setting, the smaller the aperture. The smaller the aperture, the less critical it is to focus precisely.
Street photographers traditionally will set the lens at its hyperfocal distance. This distance depends on the lens focal length and the aperture but the basic idea is that it is the closest distance setting for which subjects at infinity are still acceptably sharp. With fast film and a sunny day, you will probably be able to expose at f/16. With a 35mm lens focussed to, say, 9 feet, subjects between 4.5 feet and infinity will be acceptably sharp (where "acceptable" means "if the person viewing the final photograph doesn't stick his eyes right up against it")."
This is a big area of development for me as my comfort zone is to shoot on the widest possible aperture and preferably with long lenses! I can't seem to find any wide angle street photography images that I am even remotely happy with.
The advantages are: feeling very involved - high drama shots sometimes with a feeling of danger or excitement, lots of information being included in the image to hold the viewer's attention, a more authentic/truthful feel to the image as the photographer has less opportunity to editorialise through choice of what appears in the image.
Problems include distortion, a chaotic feel to the image, a standard 'photo-journalism' perspective which at worst can look like a picture from a local newspaper.