As a person who has anther blog I think that comments are so relevant. It reminds you that you are not just typing nobody but there are actually people reading. On cool cat teacher blog, I think that she has a good point when she says that you shouldn't be afraid to comment. I write about people that are in my life, job and etc. Most of my followers are those people who know me and comment to me in person. It is more fun for them to comment on the blog for all to see. I also LOVE that they really enjoy it. My blog is meant to be funny so know that I am hitting my mark is very positive!
I also am a firm believer in that if you wouldn't say it to the person's face you shouldn't write it in the comments section. There is no reason to be rude! Good thing they have the comment moderation section! You can never take it back once it is out there on the net!