From what I understand, it at least has end-to-end encryption by default. Like any app, you should be careful giving it any sensitive permission. However, if it is the main messaging app in your country, it might be hard to avoid altogether.
I would still encourage others to use Signal when you can. You can explain to them that it is important for you personally to use a more private and secure messaging service. You can always help them to install Signal and get it set up, and even exchange a few messages whilst you're in the same room together. That is what I have tended to do with my family and friends, and it has worked quite well.