One of the things that I, as an unabashed draenei lover, got to experience in Shadowmoon Valley during the alpha/beta test was that of several holy crap moments one right after the other. Characters that were supposedly dead long before were alive. Specific plotlines exposed the origins of enemies from The Burning Crusade or at least shed some light on them. There's a whole new aspect to draenei culture that has never really been covered in any detail before, because all the draenei we know were the last remnants, refugees from a genocide that hasn't happened to these draenei, and may never happen to them now. It's kind of like story fireworks, in a way. In a good way, but still, very surprising to see it. We didn't really know anything about the day to day of these people -- traveling in Shadowmoon, you see roads they built, buildings they constructed. They had a whole society, and for the first time here it is, ready for you to step in and defend it.
Frostfire Ridge has some surprises as well, if you're an old school Horde player and interested in the whos and wheres of certain Horde figures. But for me, it's all about SMV.
Do you pay attention to these kinds of story beats, or are you completely uninterested?