Pinterest for backlinks!

Being somewhat new to SEO and building websites, I have recently been experimenting with Pinterest and some other sites to get backlinks to some of my websites. They are fairly niche, and easy to rank for. I heard that if you share a link on Pinterest and somebody else shares it or likes it, that makes your link that much more valuable. Is this the case? Before I spend tons of time building up a Pinterest or Tumblr page, I want to make sure it is worth my time. Any advice helps!