I played the Japanese version of this one when knew absolutely nothing about Final Fantasy and barely anything about Japanese language. Despite that, the game was highly addicting. A mix of RPG and fighting game, two genres I couldn't even imagine working together, served with cutting-edge (by PSP standards) graphics and stellar soundtrack.
Eventually Dissidia was replaced by Duodecim, which is a better game all-around, so there is no real reason to bother with this one anymore. Unless you really miss the old Bartz.