Facebook isn’t just a broadcast medium, but a two-way conversation between your and your fans. Communicating directly with those who Like your Page by replying to their wall posts and comments on your Page updates can help fans feel appreciated, increasing their loyalty and the likelihood that they’ll follow your calls to action.
A good article on how your company should respond to comments on Facebook Pages
Covers: When To Engage
Constructive Negative Comments
Conclusion and Priorities