Frankly, the aspect of Shadowlands I'm most excited about is an overhaul of the leveling system—something that wasn't a part of this demo in a major way. This kind of breaks the rules of a hands-on article, but I want to take an opportunity to talk about it and why I think it's interesting, regardless, since it came up in my interview with WoW developers.
The experience curve is adjusted to make it faster than ever to prepare for the newest challenges, and each level along the way will provide more meaningful increases in progress and power. All expansion zones are getting more flexible, too; they'll be able* to scale to you and your friends while you level to 50, so it's easy to try a zone you've never played.
The spell called "spiritual projection" or "astral projection" brings the caster to the Twisting Nether instead of the Shadowlands; and the Twisting Nether is also referred as "realm of ghosts". However, both planes don't appear to be related, as Outland is floating on the Twisting Nether, but the Shadowlands can be reached in Outland in The Burning Crusade.
After rumors about this possibility for the last several expansions, Blizzard has finally followed through on a level crunch. Whereas characters in the current Battle for Azeroth expansion cap out at level 120, the cap in Shadowlands will be 60—just as it was when the game first launched and just as it is in World of Warcraft Classic. Level-120 characters will be scaled down to level 50 when Shadowlands launches.
Sylvanas Windrunner, fallen leader of the Horde, has pierced the veil between Azeroth and the realm of the dead, setting in motion a series of events that threatens to upset the cosmic balance between life and death. World of Warcraft players entering the fabled Shadowlands will find the realms of the dead in upheaval. Under the normal order, departed souls were delivered to a realm appropriate to the lives they led, but now, all souls are being funneled into the Maw, where the most wicked are damned to suffer for eternity. As they seek to right the cycle and uncover the extent of Sylvanas' designs, players will forge bonds with the Covenants who hold domain over different planes within the Shadowlands.