How can that feedback be helpful to you? he is just saying your service should not exist. I think instead of bending down and take it and being nice you should prove him wrong by arguing the WHY USE of your product.
PS. Our USP is 'Create a complete personal website'. Sprred is more than a blog, it's your blog+photostream+videostream.
Your response here tells everyone: yeah his right you should come back when I have made the magic work according to this guy. What you don’t know is that the guy will criticize you anyway because he is actually criticizing your existence. My take is you should not let that happen.