For a multimedia story to be successful it requires, firstly, a combination of media. This merging of media and possibly text have to all work in a cohesive fashion and work toward a goal. For it to be successful, as well, it has to have an impact on the viewer; be that impact emotional, informational, or some other form the viewer should walk away with something more than what they had before viewing the story.
A story I feel that does exceptionally well is by the New York Times regarding Mexican drug cartels.
The story not only informs the reader but allows them to see how it negatively affects the people living in the border states as well as in Mexico.