Not a very bad application though but still there are many factors which still need to be highlighted and talked about.
The application have various bugs such as sometimes the messages you sent never get delivered. You can wait till your death but they will not and sometimes you don’t receive messages sent by others.
You will think that the other read but didn’t replied but the reality is that Facebook messenger didn’t showed you the message as it is lost somewhere in space.
Calling feature is good but still not that clear.