It’s a good one (Signal as well, though). My favorite design decision was to tie it into the email ecosystem, so if anyone tries to block it, they will have to block email, which their business buddies won’t be happy about.

Some more here:

https://media.ccc.de/v/36c3-oio-154-delta-chat-e-mail-based-messaging-the-rustocalypse-and-ux-driven-approach-ybti-wefixthenet-session-