It is not considered a good alternative as a messaging app for privacy folks and because the source code is not open, it is not E2E encrypted by default (you need to start a secret chat or something to make your conversation encrypted) if I remember correctly.
And it will not get upgraded to 20.04, it will stay on 16.04. My biggest issue was that I could not do much with it. It was only a bit better than a dumbphone. Without apps, every mobile OS dies and back in the day I could not even get Signal working. It was a pain to set up webdav for contacts sync and when I gave up and wanted to use my own nextcloud, it refused to work because of my https cert…