i want to like signal but the UX is wanting. i installed it today and it only imported some of my sms messages; found almost 1000 open issues on github. then i sent the "get signal" message to a friend who installed it but our messages still kept saying they were insecure sms. turns out we had to "refresh" our contact lists (there is no menu option to do this, you're just supposed to know to pull down on the contacts…
Contact discovery can have a slight time delay, but so far it has worked very well after a while. (I don't use SMS)