Even if MTProto is insecure I want someone I trust to tell me so.

it's very likely insecure but the amount of negative press on the subject of telegram is worrying, would you rather people use whatsapp?

I know they're not touting themselves as the bastion of security (like telegram does) but I'd rather people used telegram because at the very least the protocol is open source, and once they have federation and a released server it will be possible to improve on the security probably.