ASK HN: Social Media Opportunities: Measurability, ROI and Worth in 2014

Heyho, i'm looking for a good overview about the power of socal media in 2014.

How can you measure it, what value do the measurements have, what opportunities are out there?

Can you suggest me one or more good & up-to-date overviews (links, blogposts, recently published books...) that are not completely interspersed from pr lobbyists?