The only problem with this is that it only allows you to have conversations in public chat rooms. In other words, FireChat users cannot have private conversations with their friends. Instead, you will have to talk in those chat rooms, with all of the problems that come with them.
Another big advantage of FireChat compared to all of the other messenger apps is that it doesn't ask you for any account information. You don't have to register using your phone number, your Facebook account, or anything else. You just have to enter your name and you're in.
FireChat is a curious messaging app that is more of a tool to satisfy your curiosity and see what people around you are talking about, rather than a traditional instant messaging service.