Beyond this point lie some fairly hefty spoilers for the early part of Warlords of Draenor, so if you're trying to avoid those, pass this article by!
Thanks to the Iron Horde, Nethergarde Keep is now a ruin, resembling the less-fortunate parts of its twin, Honor Hold, more than anything else. Take some time to mourn if you need to, then check out The Shattered Beachhead, where you'll find Vindicator Maraad, an SI:7 agent named Bodrick Grey, and a whole lot of Stormwind marines. The Alliance and Horde fleets are parked offshore, and it's clear this counter-invasion has been done by sea. There's also a new flight point at The Shattered Beachhead to replace the one lost at Nethergarde.
Maraad and Bodrick give you some standard quests--Maraad wants you to kill Iron Horde Grunts and destroy their siege engines. Bodrick wants you to find his missing scout, Pazerp. When you do come across the poor gnome, she's dead. Archmage Khadgar shows up to reiterate the obvious, and you take a gander through Pazerp's telescope to see hordes of the, well, Horde (Iron edition), pouring through the Dark Portal. In the beta, the Dark Portal is still green, but the quest text indicates that it's supposed to be red, so I imagine that change simply hasn't yet been implemented.
When you get back to the Shattered Beachhead, your next quests involve taking out Iron Horde Scouts, who are disrupting Maraad's battle plans, and Ironhand Executioners, who are killing the Nethergarde POWs. Once you silence the scouts and rescue the POWs, Maraad tells you to meet him behind enemy lines at a small camp in Dreadmaul Territory.
At the new camp, Maraad is joined by Commander Vines and Enohar Thunderbrew, a Nethergarde survivor and former questgiver there. Maraad and Vines give you quests to go back into Nethergarde and reclaim it. You kill Iron Horde commanders and steal their battle plans, rally Alliance troops to fight, and retrieve mementos of the fallen Nethergarde defenders--Strumner's Sword, Keri's Mug, and Krolan's Shield.
The Iron Horde battle plans inform you that they have allied with the Dreadmaul Ogres. Maraad sends you to take out a bunch of Dreadmaul plus their leader, Toothsmash, while Enohar asks you to avenge her sister by poisoning the ogre's food stocks. With pleasure, Enohar. After you've done all this, the quest chain culminates with you and Maraad taking out the leader of the Iron Horde in the Blasted Lands: Gar'mak Bladetwist, located in Orkril'lon Hold. Once Gar'mak is dead, Maraad sends you back to Stormwind to report to Varian Wrynn. Here the quest chain feels unfinished--when you turn in the quest Varian says, "We need a plan before we strke," but no additional quests or discussions of plans is forthcoming. I assume there will eventually be something to follow, perhaps a small cut-scene featuring Varian and other NPCs, because Varian's lines sound like transitional dialogue leading into another set of quests. I suppose time will tell.
Overall I like the way these additional quests give us things to do in the Blasted Lands. It makes sense that something would happen there, considering it's where the Dark Portal enters Azeroth. However, if these quest additions are in fact permanent, then revamping this part of the zone into a level 90 area might make it a little confusing for new players leveling through the southwestern area of Surwich. Be careful not to run too far east, lowbies, or you might be in for a nasty surprise. There's also a lot that feels unfinished--for example, another level 90 quest on the Hero's Call Board in the beta tells you to go meet Khadgar at the Dark Portal to begin your excursion into Draenor. Currently there is no bridge between the Blasted Lands quests and this quest. The natural place for this link to be is after you speak to Varian, of course, and I assume something eventually will happen there, but there's nothing yet, so for now it feels disjointed.
Furthermore--and I can't help but think this is a bit like beating a dead horse, here--but it's tiresome to see yet another Alliance hub destroyed and removed from the game. In Cataclysm we lost Southshore and a good chunk of Ashenvale, in Mists of Pandaria Theramore was destroyed, and now Nethergarde Keep is destroyed. Fortunately, Nethergarde is less of a loss than Southshore or Theramore, considering that it's not as major a point of access as the other two, and the flight point is replaced. Still, as an Alliance player, I'm getting pretty tired of permanently losing towns and cities to the Horde, Iron or otherwise. That's why part of me wants to hope that these changes to the Blasted Lands are temporary, but we'll just have to wait and see.