Information known at time of creating this thread
Note: Some of this like loot 2.0 is probably PC specific since consoles are already getting some of the tweaks.
Important Characters:
Malthael, the former angel of Wisdom is seemingly the main antagonist.
- Angelic wings of bone, dark and grim appearance. Can drain life and so on.
New class:
Crusader.
- A mid-range class with shields, flails, and heavy armour.
- Very paladin-esque.
Abilities include:
- Shield bash.
- Fist of heavens.
- Shield's Flare.
- Falling Sword.
- Law of Valour.
New Area:
Westmarch.
New Level-Cap:
Level 70.
- More skills.
- More runes.
New Monsters:
Confirmed so far:
Seraph.
Summoner of the Dead.
Executioner.
Death Maiden.
New Items:
Confirmed so far:
- God Butcher (Flail).
Mentioned:
- A Wizard wand that now has a greater chance of summoning hydras, and more of them.
Story:
Malthael wants to end the eternal conflict by destroying all demons. The Black Soulstone is meanwhile hidden somewhere on Sanctuary by the angels and the Horadrim. But as we see in the opening cinematic, Malthael steals it, nearly killing Tyrael in the process.
Loot 2.0:
- 'Smart Drops', items drop less but when they do, there is a chance stats are tweaked to suit your character.
- Less 'junk' loot (white, yellow, etc.) - but the stuff you do find can be 'Smart Drops' sometimes.
- 6 new Legendary items.
- Legendaries will be build-changers.
Paragon 2.0:
- Now account-wide.
- No longer a cap (!).
New Artisans:
- Transmogrification (change item looks).
- Enchanting (re-roll a rare legendary affix).
Loot Runs:
This is a new feature with randomized 15-20 minute dungeons to mix up the endgame a bit.
Other notable features:
- More focus on endgame variety.
- Transitions between external and internal locations are now seamless.