For me and a lot of my friends the increased popularity of Instagram is entirely about how we hate Facebook but don't want to abandon our FB connections. So we

For me and a lot of my friends the increased popularity of Instagram is entirely about how we hate Facebook but don't want to abandon our FB connections. So we use IG as our primary way to say hello, send an update, and register a Like. And then we go on FB when we have more time, or want to share a link, or whatever. But this is less and less common, judging by the relative activity I see on IG vs FB for my own connections. (And even a lot of the regular FB users are cross-posting all their photos now.) As such it's not that great a photo-sharing UI, but it works and it doesn't require Yet Another Social Graph. I don't know how much this is a factor in IG's continued growth in the face of Snapchat -- after all I'm talking about a cohort 30 and older. But my gut tells me it's significant.