Instagram has literally exploded all over FB specifically my FB. I don't really see the appeal of it make your photos look aged. I thought people got past taking photos that look age after the polaroids died off years ago. Perhaps it's nostalgia these photos like the polariod had, a certain style and a certain age that can be tied to Americana the "good old days."
I found this article that I liked on the matter.
I don't claim to be a photographer well not since High School, I have dabbled in it as a hobby ever since. Personally and this may just be me; the instagram is to photography, that lens flare is to Photoshop. Again I don't like this style but tell me what you think? Love it or hate it, people are interested in photography more now.