Well, if you look at it that way, there are overlaps with most social networking services- Facebook also uploads photos, shares with friends, and people comment on them.
What we'd like for Persona or at least how we use it is a way to share our personal interests and connect to people through them. Sometimes when I pull in front of a starbucks in my 87 mr2, people stop me, pull out their phones and show me their mr2s as we talk about cars. I'm attempting to mimick that real life conversation by posting photos of what I'm passionate about, or what I want to talk about on my Persona, a visual diary of my life. People respond using photo comments that shows me their perspective of that shared picture.
It might be a far-fetched goal, but I hope that people all over the word would be able to bond and share a connection over a single photograph that you post. Like a real life conversation when you first meet someone, I want people to be able to recognize and find a common point of interest as a topic to converse upon.
This might be subjective, but from how I use Instagram and how I see most users use it- it's to post random pictures that you encounter, more to showcase your photographic skills rather than to show what your life is about.
