If there is one place where people feel truly free to say exactly what they think and how they feel it's on their social media platforms. Be it Google +, Twitter, Facebook, Pinterest, or whatever. What people are saying on social about you or about companies and products you represent can make or break you in terms of success.
If you want to know what people think about a product they have tried or questions they are asking about a product then staying in touch with what's happening on social can be a huge thing for you.
There are tons of ways to track what people are saying in twitter for instance Social Oomph and Hoot Suite both have free accounts you can sign up for and they both have a feature that allows you to search keywords and see what people are saying about that keyword.
Pretty much whatever people are saying on twitter they are saying everywhere else as well. This is a gold mine of information that you would be crazy not to take advantage of.