Kaivax, a WoW forum community manager, revealed that WoW Classic's class design, battleground mechanics and stats on existing items will be set to their 1.12 state, despite the game releasing content that expands beyond that. This removes "progressive itemization," so if the stats on a specific piece of equipment was changed during the original updates, that won't take effect in this version.
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.
Keep in mind that these quests are optional, and are not necessary to continue leveling and capturing companions. They are also account-wide, so if you complete the quest chain on one character, you will not be able to complete it again on another. However, any progress that you've made will be saved and you can pick up where you left off in the quest chain on another character. The dailies that you've unlocked will also be accessible by all your toons.
Arcane: Arcane Empowerment - Clearcasting can now stack 2 additional times, and increases the damage of Arcane Missiles by 5% per stack. Clearcasting no longer reduces the mana cost of Arcane Explosion. Fire: Flamecannon - After standing still in combat for 2 sec, your maximum health increases by 3%, damage done increases by 3%, and range of your Fire spells increase by 3 yards. This effect stacks up to 5 times and lasts for 5 sec. Frost: Concentrated Coolness - Frozen Orb's damage is increased by 10% and is now castable at a location with a 40 yard range but no longer moves. Monk
It was the experience of the game that brought pleasure and joy, and that's what a lot of us want again. Not the numbers. When I play Classic I want to go through the deadmines with people I like and overcome a challenge together and see myself become stronger as a result. I don't want to play Classic so I can say "booyah! That number is exactly the same as it was 13 years ago!"