I tried using it with a friend, and it completely nuked my phone’s battery, while my friend’s phone silently killed it (likely for using too much battery). I understand that truly privacy-respecting messengers will always use slightly more power than apps that use the google notification thing, but simplex is just a complete power hog beyond any reasonable limit. Hopefully they fix it at some point, it seems like a pretty solid messenger otherwise, and their approach to privacy and anonymity is unparalleled, at least in theory.