I'm using molly for a few months now. No problems really. Using it to talk to a signal user. What I did notice is that there are less "wifi low, switching to data" messages now. Had those regularly while using the official Signal app, even with full wifi reception. Since I switched this happened only once or twice.
Also significantly less times that calls were ended when being on a call with somebody over night and just letting it run to continue speaking the next day. With the signal app it happened a lot, call ended and signal closed without any notification. With molly that never happened so far.
So tl;dr: Can only recommend
Why does he not simply walk on the water?