So I'm at my quitting point after playing for just under a month after a few years away, here are my thoughts:
I like the mob scaling so that you can choose levelling zone order and come back later for daily quests. I also really like the design for daily quests being on the zone map and rotating every day. The quests with a progress bar and secret chests and rare bosses are fantastic for replacing all the bear asses filler. There's also some good things going on with the story. All this is MUCH improved from earlier expansions and I like how they kept the improvements from MoP/Warlords/Legion and built on them.
The "world" of warcraft is dead and I don't think they will ever recapture that vanilla feel of this incredible huge world, each expansion feels much smaller than the original vanilla world. They did a good job getting rid of flying mounts by gating them, but being able to teleport to dungeons from anywhere still devalues the geography. Cross-realm means there's no real sense of community, there's no prestige guilds on your server to avoid or aspire to join. I'm mostly neutral wih this, making it more user friendly has made it easier to play the actual game at the cost of immersion and what makes MMOs special.
What is absolutly godawful and worse than it's ever been is how you progress your character. Gear is so, so boring - just incrementing that item level. Talents are boring with set choices of three and weak artifact abilities, Diablo 2 invented the industry standard for this and they WENT BACKWARDS with it. Just LOOK at what Path of Exile is doing with gear and talent points, holy shit. Why can't I make a leech set for my disc priest for PvP, or a tank set and have some unconventional dungeon runs? Have some diversity in stats FFS! Most fun I had in WoW was tanking Stratholme with my Priest using Mind Blast to catch threat and Vampiric Embrace to heal myself and survive that way instead of mitigating the damage (though I had Inner Fire for armor). They've nerfed anything like that away for boring...
As much as there is to do in the zones, there's no point if I don't feel like I'm improving my character. Having mob scaling and no character progression just means we are still effectively at lv100 and feeling our characters get weaker as mobs strengthen to lv120.