Well after wasting way too much time instead of doing more important things :P, I can say that SoU is rather good for it's Campaign. Better story, more role-playing and thoughtful options, memorable and interactive henchmen, no +2 swords lying in a barrel in an ally, no respawn, actually somewhat challenging on only hardcore difficulty! The tilesets are nicer than I thought, although I keep going "WTF" when I see a western stone building (ripped straight from the city tileset) in the desert next to people in turbans and veils. Some of the character building options and spells are pretty cool, aside from the completely-unbalanced dont-think-it-even-exists-in-DND Issac's missile storm, and the messed up Bigby's stuff. Also annoying how most of the good portraits were reserved for NPCs. I can see the exotic settings being somewhat limited for the module-builder's purposes, so we might not see as many modules built with it, although the difficulty in having simulataneous installations or messing with batch files alone will probably make people use the expansion anyway.
In summary, if you want a strong 25 hour, likely 2 or 3-time playble campaign, this is the way to get it. Not sure what future the pack might have as far as the modders go though, but you can always take your SoU abilities into NWN modules and taunt other people. :p