SoU doesn't seem to add that much; I'm not too keen on prestige classes. (I'd rather that they extend the level cap. I'm not a powergamer, but the with the limit at 20, the game is rather limited. Damn you, Bioware, the Epic Level Handbook is out there. Make bloody use of it!) I might buy it if I have nothing else better to do, but it depends on how solid the SoU official campaign is. (Which it doesn't seem to be, as far as I can see.)