I recreated my very first character -- a human warrior, because in the last-push alpha test I joined in 2004, there was no Horde -- and logged in. Immediately, I was surprised by how good the graphics actually looked, for being 15 year old textures-on-polygons. Warcraft's bright colors and cartoony aesthetic continue to this day, so all the increased resolution and better-contoured characters in Lordaeron don't really change the game's visual aesthetic.
Recently the new essence received from PvP which gives you access to an extra PvP talent, that also works in PvE situations, has made waves and there are plenty of threads about it on the forums. One in particular got a blue response which clarified just how powerful and how relevant the essence is supposed to be for PvE-focused players. Each spec gets a specific PvP talent added and some of them currently selected on the PTR are a little too powerful and feel mandatory for PvE, such as Moonkin Aura for Boomkins and Leader of the Pack for Feral Druids, but Blizzard clarified it is not their intention to have must-have talents for PvE available through the essence, as its primary goal is to add additional choice for PvP players.
Arms: Sharpen Blade - When activated, your next Mortal Strike will deal 15% increased damage and reduce healing taken by 50% for 6 sec. Fury: Battle Trance - You go into a trance causing you to regenerate 3% of your health and generate 5 Rage every 3 sec for 18 sec after using Raging Blow twice in a row on a target. Using Raging Blow on a new target will cancel this effect. Protection: Thunderstruck - Thunder Clap roots all targets for 1 sec. You can find a list of all Essences available in Rise of Azshara here.
This Shadow Talent Build is the fastest for Leveling Up a Priest Class from 1-60 in WoW Classic patch 1.12. Spamming Shadow Damage DOTs while kite mobs will be the name of the game with this build, having the ability to sustain your health is just a bonus. You will just need to make sure you are stacking enough spirit so you don’t run out of mana often as that will slow down the levelling process drastically.
That's not to say that everyone has an unrealistic vision of what vanilla WoW was like. There were already plenty of people on the WoW Classic forums pointing out that perceived bugs are just recreations of the original game. And as noted before, a flaw to one player is a key component of the original positive experience to another. WoW Classic will surely please plenty of purists in spades. But this goes to show that it won't be for everyone who has fond memories of the game circa 2006.