I've published an article asking this very question on Photocrati.com, a pro photographers' blog, gear review site, and community, which includes this:
"Multimedia is not a panacea for ill thought out or badly produced projects. It still needs good stories, great photographs and certainly, audio that is part of the story and part of the photographs. Adding a song downloaded from an online music store to a set of unrelated photographs is not what I’m taking about."If you're interested in producing your own audio slideshows, I encourage you to read it here, and by having a look at an earlier POV post of mine here on TTP.