Hello, I am a co-founder of P2PCoins.io. We are happy to receive feedback and answer some questions.

1. Testnet issue - sorry for that experience. It is not very stable mostly because of the issues with bitcoin testnet itself and also because we do not give it a priority right, you are the first user on testnet and it is possible that the service was down and we did not notice. That is on us.
2. Creepy vibes - we want to do acomplete re-brand and make our cat more friendly :)
3. Cookies - We have google analytics cookies, which you can block if you want and then cookies related to user like Session ID (necessary to log-in).
4. Not able to make trade - I think you have chosen a non-available trader then. Since launch which was about a month ago (we are very new) trades in total of ~30k€ were done.
5. Open source - this is planned.
6. Application error: Feel free to share an error you were seeing.
7. We DO NOT offer any coins and do not plan to. We believe in BTC but we also think XMR has it's place, at least now. We will likely drop the ETH implementation.