I've never used it because it won't even run without some kind of Google infrastructure installed. I nearly fell out of my chair when I saw that error message on my CyanogenMod phone a few years ago after excitedly trying to install it for the first time after jumping through the hoop of tracking down a trustworthy APK (which, at the time, the Signal project did not distribute themselves, don't know if this is still true) to avoid having to install the Google Marketplace. I'd never heard of it having this dependency, and so many seemingly privacy-knowledgeable people seemed to be recommending it that I figured it must be a good thing, but a privacy app that depends upon Google is a bit of an oxymoron for me.