The fact that it is very easy-to use as well; I mean there are no complicated menus or anything like this! It's just great because you don't have any problems when connecting from mobile devices such us smartphones etc., You also do not need an expensive server at all (which would cost hundreds if needed).
There isn’t much i dislike about mqttchat but maybe some more features could be added? Maybe even better support during certain times/days should help out people who really want their app working 24hrs / 7 days per week ;-) As stated before though - everything works perfect so far which makes me happy :D.