Post comments quickly without leaving or refreshing the page.
More than that, it checks if all fields filled correctly, and also makes sure to avoid comment duplication, and has flood protection capabilities as well.
Probably one of the best ways you could spice up your WordPress Blog with AJAX; readers love it! Must see for yourself.
Ajax Comments known to work well, with Authimage plugin, but I rather suggest Akismet, as it is free for personal use.
* perfectly compliments any well-styled comment form design-don't design without it * best when moderation is off (seems more real-time) and AuthImage is installed (self-moderation is the best moderation)