It has several different combined background/transition options, but not an overwhelming amount and has a nice little music library divided by theme/mood. Users can use the available graphics, upload photos, or add text to one of a few different slide formats, record audio for each slide, and either use the provided music or upload their own. It even has a few pre-made story structures, such as "Teach a Lesson", "Show and Tell", and "Explain Something".
It also has a built in tutorial that walks you through how things work the first time you use it. No need to spend time teaching students what to do! Best of all, it's so easy to use, even a Kindergartner could use it!
The only real downside is that you can't download your completed video, but you can share the link by copying it to the clipboard, emailing it straight from the app, embed it, or share it out via Facebook, Twitter, or SMS.
I was able to make a video explaining Blended Learning in about 45 minutes (would be faster now that I know how everything works.)