Some of the cool features that IntenseDebate brings includes:

• Comment Threading – this allows you to add a comment to the general discussion, or just reply to one comment that needs a reply.
• Reply by E-mail – the reply by e-mail feature makes it super-easy to stay in the conversation.  You can respond to and moderate your comments with the ease of just replying to an e-mail.
• Importing and Exporting – the best feature of all, the import and export feature is nice.  It gives you a “way out” just in case IntenseDebate doesn’t tickle your fancy.

You can read about the other features, such as reputation points and commenter profiles here.   There is also a ‘bit of a social network thrown into the mix too – which is a nice touch.  You get your own profile page, where people can find where you have commented and who you are following. Here is my profile as an example:  http://www.intensedebate.com/people/cheasym

Sign up is easy (especially if you have an Open ID) and they walk you through the steps of adding it you your blogging engine of choice.