1. Do you need to "log in" to use it? Or can it be used without an account?
2. Can you have hidden/secret conversations? That is, the conversation isn't easily observable by everyone within 1km?
If one wishes to continue a conversation one-on-one I believe other applications are better suited for that. I therefore build only one private function:
The exchange of contact details if both parties agree. If one wishes to participate in an exchange of details. It is also for this function only required to fill in some form of details. The idea being you can than continue your conversation in private elsewhere.