I've seen another app very similar to this (forgot the name). I'm fascinated by the movement toward "mashup products" that take two pieces of media and create something new (e.g. Mindie w/ music + video, Gifsound w/ GIFs + music, Context w/ photos + text).
That said, the creation of each Flipagram is demanding and we aren't always in a situation/context where we can listen to audio. Ie, volume of creation and consumption will be far less than something as simple as Instagram so to make up for it, the content better be super compelling. And I'm not sure it is.
Flipagram rumored to be raising $50-60M from Sequoia. Wow. http://techcrunch.com/2014/02/04/source-flipagram-raising-50-60m-at-300m-valuation-from-sequoia/
Kam Bain ✍
@rrhoover That's a HUGE round for them. Kinda surprised it's so much. They must have some massive expansion plans because the app is fairly elementary.