I think citizen journalism can be helpful to traditional journalists. Of course, there’s the normal stuff that was already said, like how people on the scene can take videos and photos and share them with the press, who can then distribute the photos. Or, if something bad happens, people can tweet about it, and others can learn about an event by looking on Twitter. By going through these public sources of information, news media can get a wide array of eyewitness reports to help them form a report of what happened at an event.
Some disadvantages would be it could violate a lot of people’s safety. If something happens, and everyone starts gathering around and filming it, it could prevent the proper authorities from getting to the place of danger and resolving the situation. Also, if people just stand there and film and there’s something like a series of explosives going off, they’re violating their own safeties by standing there and filming, rather than getting away and starting to film.