@Additions:
Added a shared stash! You can deposit or withdraw items to it, and share between save files.
Added elemental damage resistances and bonuses! All spells have also been set to certain elements, unless changed through specific equipment. 
Note: a future update will allow a much broader variety of elemental types on each class' spells - some elements are underrepresented at this time
Added new enchants for the new stats, +Element power is considered Major and +Element resistance is considered Minor, so you can roll both on the same item
Monsters now have a type listed among their mods, for example "Undead" meaning certain base elemental resistance or weakness, in the case of Undead they are weak to Fire. The rest is for you to find out!
More types like these will be added over time.
@Balancing:
Enemies now only scale after your equipment on Casual and Normal difficulties (instead of all, was too easy)
Difficulties above Normal have been adjusted and should prove more challenging
Difficulties above Normal now also set a minimum elemental resistance to all enemies (0,0,10,20,30)%
Champions have a base minimum of 10+difficultybonus% resistance
Chests are much more likely to become locked and require the keys (and hence award better loot)
Higher difficulties now increases experience gain by a set amount visible in your stats screen (0/0/10/20/35)%
Crystal gain is also increased in the same way with higher difficulties, now (0,0,15,25,50)%
The Experience required has been increased, especially on higher levels
Thorns/reflect damage can no longer crit
Damage over time effects now have their crit chance determined by their type; bleed 20%, burn 10%, misc 5%, poison 0%
It is now slightly harder to find Legendary and Unique equipment without increased +Magic find, overall item quality roll chances has been rebalanced a bit
Templar and Berserker have some base resistances to account for them being melee classes. (15% and 10% respectively, to all elements)
All accessory items have had their stats rebalanced and in general been made more useful
Slightly increased proc rates of some damage enchants (chain lightning etc)
Reduced item sell prices
Increased power of Mana potions, especially high level ones
Healing potions now heal half instantly and half over 5 seconds, but they heal the same total as before
Changed how experience gain from killstreaks are calculated, and reduced it a bit, but now you get more bonus exp per kill the longer the streak is
@Items:
All Unique and Legendary items have changed or been granted additional enchants - Unique and Legendary items are now more powerful but also more rare
Robe of Corruption now causes poison damage to attackers, rather than just "damage"
Added 7 new Unique items found on Unique monsters spawning randomly in selected areas
@Spells:
All spells have had an "element" set - increasing the relative element power will increase the damage output of all spells of that element
Many passive skills that previously made certain skills deal more damage now instead grants elemental power in the relative element, stacking with any equipment enchants
Spells that appear on or over targets and now line of sight based - so if your character can't "see" them, eg behind a wall, you cannot cast at them. The spell willl and at whatever is blocking the view instead.
Note: this is primarily so that Warlock and Warden aren't able to cast spells on other sides of walls - you should still be able to reach enemies hiding behind single pillars (cause otherwise it would be annoying) - consider this feature experimental..
Infernal Demon is now more clever and does not use his abilites unless someone is in range for them
Templar's Barrier now grants elemental resistances instead of flat damage reduction
@Monsters:
Monsters have gained base resistances to various elements
Champions may roll a resistance affix for further increased resistance
Champions have a minimum resistance of 10% to all (scales with difficulty), meaning weaker monsters like Bats aren't as easy to kill while as champions (but still easier than most other champions)
Monsters labeled "Minion" are much weaker and has now a reduced chance to drop loot
Medelee (boss) will cast many of her spells more frequently
@Areas:
The Treasury now only spawns rare chests!
@Interface:
Hoving an accessory item now points arrows to both slots, the one being compared to being opaque and the other transparent
Adjusted some more text color values
The difficulty select screen now display how much magic find, crystal find, and experience gained you get as bonus.
Health and Mana regeneration is now visible on health and mana bars (estimated value next second based on current regeneration)
@Misc:
"Minions" are renamed "companions"
Short duration companions are called "summon"
Collision checks updated, cannot get pushed around with big enemies ganging up on you any more, and you'll always slow down if you collide with something
Explosions now cause a large amount of light to burst
Added help index on the elements
@Fixes:
Fixed a drawing depth issue with satellite enchants
Nova spells (monster's) no longer spawn all projectiles at dead center, meaning you are less likely to take them all to the face (because that hurts)
Fixed issues with collision boxes and hit boxes on certain up-scaled enemies
Fixed spikes killing a player instantly when attempting to respawn on it
Fixed Templar's block not working as intended
Fixed Berserker's Fist of Fury getting stuck in animation if being knocked back mid-animation
Fixed Warlock's teleport getting stuck in animation if being knocked back on teleport end
Fixed passive effects not disappearing when using a respec elixir
Fixed chain lightning effects not being able to target the same base enemy
Fixed chain lightning enchant and orbs to properly jump 3 times as listed
Fixed bug with secret rooms being closed off and inaccessible after re-entering the zone
Pets now properly despawn when you die
Unique / quest monsters now guaranteed to spawn somewhere in each area - there was a miniscule chance they wouldn't earlier