I have been using it for a few months and I do love it. I love the ability to have visitors login with several different options, Facebook, Twitter, OpenID, etc. I also love having a central repository of all comments from all my sites in one place, as well as all my own comments that I have left around the web.
Then, after my Giveaway: Nintendo DSi + 2 Games! ($210 value!) post racked hundreds of comments, I realized that I would have a hell of a time choosing a winner due to there not being any comment numbers next to each comment. I wrote to support and asked if this was possible. It seems like a simple hack of code to me, but they say that it is not possible. I tried it based on some web notes that I found on adding numbers to your themes in WordPress, but it did not work on Disqus. Booo!!! So, unless I find some way to export my comments nice and neat to Excel format to put a number next to earth, fairly choosing a winner is close to impossible.
I'll be using Greg's Threaded Comment Numbering to get the job done with a couple of hacks to my theme. So, please hang in there while I get it done. I will have to export all my current comments from Disqus and reimport them into my WordPress. Yes, I will back everything up first. 🙂 Some day, if they add the ability to number the comments I may return to it.