There's a lot of pictures. Also these are not mine, so credit goes to whomever took them.
-A lot of trolls get killed by the Iron Juggernaut.
-Tyrande and her sentinels kill several Orcs before destroying the gates of Orgrimmar with glaive throwers.
-Vol'jin has some big siege weapons, but I'm guessing they're not effective, enough, or destroyed.
-Skyfire just flys around. Not too sure.
-Gnomes and dwarves have their own tabards, with the dwarves having dwarven shields.
-Trolls and Tauren have their own tabards as well. Also Trolls have some armor. Nothing too unique.
-We get named Troll npcs! I don't know if we know them though.
-Dranosh'ar Blockade under Darkspear Offensive control.
-There's a blind orc blademaster that we fight.
-Overseer Komak has Ji Firepaw right outside Grommash Hold and begins threatening him.
-There are dead Darkspear troll hunters and Theramore civilains tied to those pillars when you enter the city.
-Some minor orcish NPCs in Orgrimmar that are being trained by Kor'kron. They reflect their normal, low levels and are killable. The NPCs are:
Shimra <Trade Supplies>
Trak'gen <General Goods>
-Aysa rescues Ji after you kill Overseer Komak.
-Mag'har Treasury Guards
-Some of the Kor'kron have some alive Theramore Citizens in chains, making them fight each other. This probably means that's Garrosh has had many citizens locked away for months now.
-Overseer Thathung seems to be in charge of the Theramore Citizens.
-Various prisoners of the Kor'kron. Some are dead, including a troll headhunter and Thunder Bluff warrior. Releasing the Doyo'da or the Wildhammer Shaman lets them put down totems that help against the Dark Shaman bosses.
-You need a Kor'korn Key to open the cages.
-Theramore citizens say "I can't...they took my children!" as you engage the Kor'kron Oveerseer.
-Eitrigg looks injured.
-The guy you used to turn in Dungeon Set 1 gear for Dungeon Set 2 gear during Vanilla, now a boss in Mists.
So Kosak commenting on Orgrimmar being a bloodbath was correct, because a lot of Orc npcs die.
Oh and also, the warlock trainers including the demon trainers and Neeru Fireblade are dead. I think some of them are hanged too.