I gotta say that Juna has grown on me a lot in IV. It's too bad Rean is too much of a liberal chump that doesn't support Erebonian annexation of Crossbell that he doesn't give that Crossbellan cooter a good eight leaves dicking to get her on board with it.
The thing I liked about their use of Juna it shows her to be much more than just a Crossbellian pro-independence fan girl; she shines as one of the few people that actually has a strong family nucleus from which she draws a lot of strength in the face of the impending crisis. Her interactions with Campanella (and as a consequence Mariabelle) in particular are also very interesting and she seems to have the maturity to see the issues clearly of complex characters like Musse and Cedric - it makes you wonder how they might use her as a character in other games.