What Makes Instagram Worth $1B?

What makes Instagram worth one billion dollars?

OK, I know it's worth it if someone pays that much for it, but other
than that, why is it so valuable? I've used the application and don't
find it that impressive. The few filters are not earth shattering and
the fact that they are able to post to other social media, doesn't
make it that valuable. That's just "the power" of developing a sharing
agreement with the other social media companies.

What it tells me is, Instagram has valuable metadata that people don't
realize they are accumulating and/or creating and Facebook gets access
to it. As I type this, the Instagram website is not responding
probably due to the crush of requests.