Since this was an early questing experience and not an endgame one, I didn't get much sense of how Covenants—Shadowlands' new Order Hall, Garrison, or War Campaign-like systems—work. Neither did I have much time to dive into the story, though I saw enough to know that, if you like the flavor of the recent WoW expansions, you'll probably like this one, too. (I, for one, am glad we're going to get a brief respite from the Alliance vs. Horde war storyline.)
Ascend the Tower of the Damned: at the heart of the Maw lies Torghast, Tower of the Damned, a cursed otherworldly prison where the wickedest souls in the universe are locked away. Highly replayable and inspired by roguelike games, heroes are invited to explore its ever-changing halls and chambers and do battle with the minions of the Jailer, Torghast's vile ruler. Those who brave its trials can claim legendary treasures and help free the heroic spirits wrongfully trapped within.
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.
Blizzard's new solution in Shadowlands is to return the level cap to its original value of 60 and to make current content appropriate for levels 50 through 60. New players start at level one, and they all play through a new introductory zone built for Shadowlands based on the quest design lessons Blizzard has learned over the years. Once they play through that introductory experience, they can then level up to 50 to catch up with current content by playing through the previous expansion (Battle for Azeroth) right away (from around level 10).
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.