Google changes search algorithm

Google has upped their game in their fight against content farms. They have just made what the company called a "subtle" change to their search algorithm that affected close to 12% of the queries.

According to the company, this update is meant to rank higher quality sites higher in the search engine results, and less useful sites that people complain about (the ones that resemble content farms) lower.

While they haven't really named this change as move against content farms and while I am still learning what those changes are (I am sure people will figure this out by end of next week, ha ha), I am wondering what you think about it or how can one even quantify the subjective quality of website usefulness?