Convincing people to use apps such as Signal is hard work and most can't be convinced. But with those you manage to convince, do you feel happy to talk to them on Signal?
The problem is these people use Signal on Android/IOS which can't be trusted and IOS has recently been in the news for having a backdoor. And it has also been revealed that american feds are able to read everyone's push notifications and they do this as mass surveillance.
So not only do you have to convince people to use Signal which is an incredibly difficult challenge. You also have to convince them to go into settings to disable message and sender being included in the push notifications. And then there's the big question is the Android and IOS operating systems are doing mass surveillance anyway. And many people find it taking a lot of effort to type on the phone so they install Signal on the computer which is a mac or Windows OS.
So I don't think I feel comfortable sending messages in Signal but it's better than Whatsapp.
These were some thoughts to get the discussion started and set the context.
Signal is not my tool of choice, so I'll answer from a more general perspective:
Having multiple friends and social groups on an e2ee chat system for the past few years feels great. Knowing that our words aren't being recorded and exploited by half a dozen companies, we no longer feel the need to self-censor. The depth and value of our online conversations have grown noticeably.
Yes, there is more work to do, both at the endpoints and in the protocols. No, not all of us have flipped all the switches to maximize our privacy yet. That's okay. Migrating is a gradual process. We do it together, helping each other along the way, rather than trying to force it all at once. Every step an improvement.