Here’s the top reasons you should consider adopting IntenseDebate for your blog’s comments:

• Threaded commenting
• Easy to install to your WordPress blog using their provided plug-in. The plug-in imports all old comments from your blog into the IntenseDebate system. When the plug-in renders the comments on the page, it uses JavaScript; however, the comments still exist on your page in HTML, which is useful for SEO purposes.
• From their site: “Look, we know that we’re not your first and we may not be your last comment system, and we’re ok with that. Our comment importers and exporters make bringing your comments with you a piece of cake, so you don’t need to worry about losing a single one.” I’ve worried about this with other 3rd party providers. What happens when you decide you’d like to switch? No worries with IntenseDebate.
• Using IntenseDebate gives site visitors an incentive to comment as it’s low friction and their comments across all IntenseDebate enabled blogs are available via their profile.
• The service supports platforms other than WordPress