SlideStory (free) is a very nice, fully automated slide show-creation tool. It lets you assemble short slide shows easily, right on your device, and the results look good.
Photos can be grabbed from your camera roll, Facebook, Instagram or Flickr. To make a show, you need at least five and a maximum of 15 slides. When you have your slides selected, you are taken to a page to select filters for the slides, or none at all. From there, you can select some built-in music that works for your subject material, and you can pick an ending slide. The last slide is white type on a black background, and there are some pre-selected slides, or you can add your own text.
From there, the rendering takes place on your phone, and you can then save to your camera roll, or you can upload your slide show to Facebook.
I liked this little app. It's a no-hassle approach to creating a quick slide show to share right from your iPhone. The slide show is timed to match your music selection, and you get nice slow zooms in and out on your images (Ken Burns effect) and dissolves between photos. I'd like to see the app let you choose your own music, and maybe add a title at the beginning, rather than just an end page.
I recently reviewed an app called MYMUSIAC (free) that has similar features, but I prefer SlideStory for a cleaner interface, although MYMUSIAC lets you use music from your music library. Shadow Puppet (free) lets you create narrated slide shows, but no music.
SlideStory requires iOS 6 and is optimized for the iPhone 5 series. It is not a universal app.