Mythic+ has some similarity to raiding, but it’s designed for just five players, instead of the 10-to-30 that can make up a raid. This mode tasks players with clearing the game’s dungeons, but with specific changes that make them harder, scaling up until it’s impossible for groups to finish. Players receive a keystone in their inventory that assigns them their dungeon, one of the game’s 10, and gives the dungeon a level. This determines how difficult enemies are and what effects might make them harder. If the group completes the keystone in time, they get a new, higher-level stone; if they, don’t they get a lower-level stone.
As for the classes themselves, they almost all play like slower and slightly less interesting versions of their Legion counterparts. This is thanks in large part to the loss of one ability from each class that came along with Legion’s own AP dumping system: the artifact weapon, which added a unique ability to every spec in the game. The loss of these abilities left most classes feeling frustrating and incomplete, and though Azerite gear was supposed to be the replacement, it missed the mark completely. There will always be one Azerite trait that reigns supreme for each spec, meaning that the frustration of that particular loop will be unavoidable as long as the system is in the game.
But the system offers a painful and mindless grind. At worst, it feels like a cheap and artificial wall blocking you from playing your character to its full potential. Levels of your heart come fast at first, but the costs become prohibitive when you get up into level 20 or so. This wouldn’t be an issue if the most powerful Azerite gear didn’t require reaching level 22 to unlock even 75 percent of their full damage, leaving players left out of features from gear they’ve already collected. This means more grinding.
Update: The reason for less experience from gathering is due to how Blizzard revamped professions and broke them down by expansion. In order to get full exp from gathering you'll simply need to find a profession trainer for the relevant expansion. (WoD you just mine or herb the first one ypu come across and the game gives you a scroll for learning WoD gathering).