When Disqus first launched, I was a little critical because I like to maintain control of comments, give commenters the benefit of Dofollow links, and ultimately retain control of their user generated content.
I now feel that 95% of bloggers should switch to using Disqus, though I have some reservations.
These are some of the reasons why:-


Friday 13th – A Very Bad Day for Comment Spammers
Nice search engine friendly links are a great way to reward valuable members of the community of any blog, but they are certainly not a right, and still find myself deleting 50+ worthless comments every day.
Most disturbing of all though are the SEO consultants and agencies who I have caught commenting on behalf of their clients, or as themselves with a link through to a client’s site. Some of them are totally dumb about it.
I now have a new comments policy in force though most of it is just a clearer interpretation of what has been in place for the last 3+ years.