I've been running through every interesting class to get their available artifacts on the alpha, in hopes that I'll find one that doesn't make me want to kill myself.
I wish I could play in Alpha, so I just base my observation on other people reports.
My class (monk) is going to suck large hairy dicks, this because I don't play Windwalker and don't give a fuck about it in general, but the pruning of Brewmaster skills and the complete shitty abominable redesign of Mistweaver, makes me want to kick in the balls the designers until they end up in their throat, so they can choke on them.
They made the most fun healer (MoP mistweaver) shift to a mediocre, but still interesting one (WoD mistweaver). Now in Legion it becomes a shitty generic healer, without any interesting mechanic, with the worse selection of utilities ever thought and losing the feature that made it the most fun healer to play when content was not extremely difficult, aka fistweaving.
Brewmaster is losing: Guard, Expel Harm, Chi Explosion, Touch of Death (why, oh why?) and probably a bunch of other skills which I forgot, even the fucking statues are becoming talents. If there is a redeeming feature of WoD it's been in tanking: it was never so fun before, exactly because I didn't need a healer babysitting me 100% of the time and I could stand against dangerous stuff on my own for a short while if I played correctly.
Legion class design has been made by a drunk dev during a diarrhea attack, it stinks so much of poo that this must be the only logical explanation. Of course paladins are never included in this shitfest, they must be the beloved children of WoW. Woe me for switching faction and class, maybe I should just go back to the orgasm that is holy/protection paladin (I should have learned during WotLK).
At my age I doubted I could get so pissed off at design decision for a videogame, but I truly love WoW, it's certainly the game I played the most in the last 11 years and the one I still try so hard to love even when design is done by monkeys flinging poo on a drawing board, I can't just avoid venting.
Anecdote on why it was better back in the days: the other day I ran vanilla dungeons on a level 40ish character. Having no run speed boost as a warrior, I couldn't even dps on most trash mobs, they were being killed while running by monk/priest/mage and posed absolutely no challenge whatsoever even in massive quantities. As a fury warrior I could even solo 2 or 3 by myself if I happened to stumble upon a few stragglers. Stratholme has been cut in less than half, Dire Maul allows for pulling half the dungeon at once, bosses in general tend to live below 10 seconds. After 2 or 3 runs I was so sad I had to stop.