With the recent updates in the Google, I noticed that my detailed blog comments were crawled and given back-links. Other comments that just described the topic within the blog were not picked up by the crawlers. Is my assumption right?
Content content content... You need to have content everywhere including inside your link building campaign. Bring good content and you will feel the results. Google values unique content a lot.
I don't think just elaborate content is valuable, it has to be at least in relation to the posts that are commented upon.