Pinterest can at least insert itself between you and products you might buy to earn referral dollars. My understanding is that for certain markets it has a lot of eyeballs like wedding planning.
Personally, I think Snapchat has the most to prove.
I think the novelty for Pinterest will wear off. There is only so much gratification in viewing beautiful pictures put together. I don't see any other value Pinterest is providing.
Snapchat, on the other hand, at least provides a communication channel for a very active demographics. Yes, it has to compete with a lot of big guys in the space, but the utility is there in the product.
You must not hang out with middle aged women much. My wife is on there all the time, planning my daughter's birthday party or getting ideas for her next craft project. My sister-in-law is the same.
I think someone said it elsewhere in the thread, they're replacing all those magazines suburban housewives used to read, and they can advertise more efficiently than those magazines because they have better data about you and can get between you and the transaction.
I see the value of Pinterest being something like houzz. You recognize products being sold inside pictures and then sell ads related it to it. It's like visual google advertising. You get the advantage of people looking for the thing that they want to look at.
Personally, I think Snapchat has the most to prove.