Heard to many differing stories at the moment which suggests a couple possibilities, its an MMO but they are purposefully making it as different as possible to other MMO's just for the sake of being different which seems to be the goal of almost every failed MMO out there. Or maybe they just haven't come up with a final setting yet, maybe they reached to far and have scaled back on what they aimed for massively. Me who knows, this is the problem with big ass games, lots reach to far, failed, end up limited and disjointed and fail miserably(Hellgate, amongst, a billion others). But Bioware don't seem like that company to me.
Problem seems to be everyone has had their own idea of a great Star Wars MMO in their head and had their own idea of what Bioware might do given a shot at it, so a lot of the guessing at what its going to be is peoples own idea's being mixed in.
Personally I don't care what its classed as, an MMO, lots of instancing, or single player only, being bioware, starwars and heavily story driven I'm fairly sure I'll love it.
I think too many people with too many preconceptions on what they think it should be, will end up massively dissappointed if the game turns out even slightly different.