The problem I have noticed so far: joining/leaving the chat room produces a lot of long notification messages in the chat room, which is very annoying for users of desktop jabber clients (Pidgin/Gajim) in the same room. These notifactions don't show up in Jappix mini. Example:
(11:38:02) thenktor-forum hat den Raum verlassen.
(11:38:14) thenktor-forum [email@example.com/Jappix Mini (1341394793465)] hat den Raum betreten.
I don't know if these notifications can be supressed by the jabber server.