This is really clean and simple to use. I tried it with my iPhone 6 running iOS 9.2.1 and older iPhone 4 running iOS 7.1.2, and both worked despite being different OS and models.
This is not one of those cookie-cutter chat apps that ask for money. It relies solely on one small ad banner at the bottom the screen. And it actually works (most other chat apps don't take into consideration Bluetooth restrictions that Apple has).
One small problem it does have is when both WiFi and BT are on, two copies of the same user are detected.
My suggestions would be to add profile pics to users, allow mesh networking so not all users have to detect each other and separate chat rooms. But I'm happy as is right now.