Its main feature, which set it apart from other IRC clients, is that it enabled comic avatars to represent a user; this character could express a specified emotion, possibly making IRC chatting a more emotive and expressive experience.
However, the method that this software used to achieve the comic effect was to prepend a small number to the plain text of the user's speech, which defined what emotion the character expressed. This had a somewhat annoying effect on non-Comic Chat users.
Comic Chat is seldom used today, perhaps because of insistence from other non-Comic Chat users that the Comic Chat mode be turned off, as some users found the superflous text annoying.