This post really hit home, as I was dealing with some negative comments on a reddit ad for my new site last night:

http://www.reddit.com/comments/tzfhy/the_hippest_mens_socks_...

I think there is a great takeaway here that negative feedback is often useful, but you should not blindly try to please everyone. For us, comments like that will certainly help refine our pricing and marketing strategies. Trying to convert that person into a customer, however, would be a waste of energy and focus.