I had Threema installed but not set up so your comment prompted me to set it up and I don't think they could have come up with a more confusing setup if they'd tried.
First screen asked me to wiggle my finger on the screen without offering any explanation. Second screen gave me a random string and told me that's my ID. Third screen asked me to add a password for Threema Safe, whatever that is. I then couldn't leave that screen at all because the on-screen keyboard covered over the next button, and the one big green button that was visible did nothing. Eventually I accidentally swiped and got to another screen that asked me what Threema Safe I wanted to use, like I have any idea what a Threema Safe is. After that it asked me to put in a username, even though I already have a Threema ID from several screens ago. Then it asked for my phone number. So now it has a Threema ID, a phone number and a username and I have to guess which of those is useful. Then it asked me to sync my contacts, I didn't do that. Finally, I got to a screen with a QR code, my nickname, my Threema ID, something asking me to Enter Code for Linked Number, and a Key Fingerprint. This thing bears only a passing resemblance to a messaging app.
Most of that setup I kind of understand, but then I'm the sort of person who reads HN. There is not a hope in hell of getting even 1% of the people I know to even make it through the setup process though.
Once inside, I apparently have one contact called ECHOECHO who, when I message them, repeat the message back to me. The messaging UI is slightly nicer than Signal and WhatsApp's though, but not as nice as Telegram's.
First screen asked me to wiggle my finger on the screen without offering any explanation. Second screen gave me a random string and told me that's my ID. Third screen asked me to add a password for Threema Safe, whatever that is. I then couldn't leave that screen at all because the on-screen keyboard covered over the next button, and the one big green button that was visible did nothing. Eventually I accidentally swiped and got to another screen that asked me what Threema Safe I wanted to use, like I have any idea what a Threema Safe is. After that it asked me to put in a username, even though I already have a Threema ID from several screens ago. Then it asked for my phone number. So now it has a Threema ID, a phone number and a username and I have to guess which of those is useful. Then it asked me to sync my contacts, I didn't do that. Finally, I got to a screen with a QR code, my nickname, my Threema ID, something asking me to Enter Code for Linked Number, and a Key Fingerprint. This thing bears only a passing resemblance to a messaging app.
Most of that setup I kind of understand, but then I'm the sort of person who reads HN. There is not a hope in hell of getting even 1% of the people I know to even make it through the setup process though.
Once inside, I apparently have one contact called ECHOECHO who, when I message them, repeat the message back to me. The messaging UI is slightly nicer than Signal and WhatsApp's though, but not as nice as Telegram's.