What comments give you is the most valuable feedback you can get. People are anonymous when they post a comment on your site and feel free to say what they really think.
From comments you get insight into what this person is looking for . We all know how valuable it is to know who your customers are. Who are the people you want to come to your site. This is your target audience.
This is a great way of establishing a relationship with those people coming to your site. It is a second chance to promote your product and brand yourself as an expert.
Don't just answer a comment and forget it. Analyze the information that person is sharing with you. Who they really are, what they want from your site and why they left a comment. Often these things will tell you what your readers want see and give you inspiration for your next post.
Always remember Google loves content and comments contribute to your content.Commenting on other peoples sites will also be seen by Google and that is another tick in your score with Google pushing closer to that page one status we all strive for.