It's kind of crazy that in this expansion we've been able to see not only the Emerald Nightmare but are now going to Argus. It's like three expansions in one.
Getting to Argus is relatively simple. Players will get quests that give them a direct boat ride to the Exodar (Horde included, of course.) The Draenei have managed to piece together a smaller vessel from the wreckage of the Exodar, this one called the Vindicaar, and this ship will serve as the hub for your assault on Argus.
Above Argus, the gleaming blue world of Azeroth is a vision of beauty on a treacherous and shattered world. Argus is a ruin, and at least in the first areas feels shadowy as you are constrained to demon-filled canyons. However, it appears that Argus is a bit like Vashj'ir, with three large sub-zones to explore. So far, the quests seem to end before getting out of the initial zone, but clearly there's more to come as we head to Mac'Aree (the ancient Eredar capital) and the zone that holds Antorus, the Burning Throne (the final raid.)
As someone who loves the Draenei and their science-fantasy feel, Argus does not disappoint. Rather than flight points you have teleportation beacons that all link back to the Vindicaar, and there's a lot in the way of crystals and space-based laser cannons.
I don't want to get too plot-spoilery, but fairly early you encounter two allied factions to aid you in your fight, the first being the Army of the Light, which appears to be composed mostly of uncorrupted Eredar (so, Draenei, but technically not) though it also has Turalyon, Alleria, and Lothraxion, the Nathrezim paladin (one of the class champions that Paladins have had since 7.0.) The other is the Krokul, who are like the Broken introduced in Burning Crusade, but these Broken have been on Argus all along, and seem to have been mutilated independently from folks like Nobundo and Akama.
It seems that as one progresses through the main questline, areas will open up for World Quests. As of yet I'm not seeing an Army of the Light quartermaster, but I suspect that that will be the new faction.
So far, it seems highly likely that Argus is going to follow more of the Suramar path than the Broken Shore path as a top-level zone. There's a ton of plot to get through and a ton of ground to cover. Indeed, I imagine that there are plenty of characters we have yet to encounter. But if you've been wanting a massive war on an alien landscape, boy howdy does this deliver.
This is one of the earliest builds of the patch on the PTR, so expect a ton of changes and a ton of additions.