Hi,

I'm also like you from WoW, stop subs after WOD is big failure for me...
Just start this game about 1+ month. (Leveling progress bit slow due to Work)

Like every1 said above 1 character can have all class, so no need for alt, pick your best race and stick with it.
Mount that we acquired from game are not account wide, but all other items from collector editions, veteran rewards and cash shops are account wide. Same like pet also(they called it minion here).

Crafting here are like puzzle, I'm still in learning progress.
I'm not sure yet about endgame content, still lvl 43 (Well cant play much... Works)
From what I have heard after one class hit lvl 50, to level other class are 50% faster because you get bonus exp +50% (no need Heirloom)

No open world PVP yet, but they got PVP similiar like Battleground.

Aggro mechanic here are bit complex.... If you're DPS always hit what TANK hit or you will steal aggro.
No add on, No build in Parser so no Recount or Skada, there will be no such a thing TANK will out-dps DPS.
Global Cooldown is 2.5 seconds it's bit slower paced and less fluid that WoW, and you cant cast sequence macro in this game.
No Flying and open world, felt too small compared to Wow's vast world.

From my perspective this game PVE is awesome and have nice story line if you follow it without skipping.
More into Social gaming experience and less Toxic I think.

The similar class.
Black Mage = Balance Boommkin.
Summoner = Lock
Monk = Monk
Warrior = Most likely DK

At least there's no Uncle Holinka and Celestalon hiding on twitter everytime balance is screwed up.
I respect the FF14 devs a lot for turning around and making a horrible game into something good while owning up to their mistake.
Doubt you'd see or hear that from Blizz.