The positives are that society will now have the chance to see a photo of something that the journalist would have only been able to write about.
Professional journalists need to be careful because they have very little in the way of verifying that these are actual photos taken from the scene of the story. In addition, the journalist has no way of knowing if they are dealing directly with the photographer with could be met with its fair share of copyright infringements. There might also be the difficulty of figuring out how to compensate the photographer.
The content of the photo may be called into question because there is not an easy way to verify that the content of the photo is what the “dealer” says it is.
Citizen photojournalism cheapens the work of professional photojournalists because it gives news organizations the option of outsourcing their photo needs to more citizen journalists.