SE ShB Rundown

The FATE System: https://i.imgur.com/fBiDBxq.jpg
-ShB Fates will let you earn currency that can be spent at NPCs for new rewards
-FATEs are unlocked by exploring and completing other FATEs, not strictly gated behind the MSQ
-FATEs tie in to the world lore

Side Quests: https://i.imgur.com/TaFkbGC.jpg
-ShB side quests will be level-synced, allowing you to access all of them from 70

Role Quests: https://i.imgur.com/cTtXIVA.jpg
-Role-specific quests to retrace the steps of the heroes of the First
-Only one quest line need be completed to advance MSQ
-New Jobs will have quests from 60-70 to “show how that job came about.”

Crafting and Gathering Quests: https://i.imgur.com/uZc2Ut2.jpg
-DoH/L will be sorted in to 5 groups
-Quests will be assigned to these groups, like Role Quests for the DoW

User Interface: 1. https://i.imgur.com/bJSofWD.jpg  2. https://i.imgur.com/6Se5fMj.jpg
-New Light Skin theme for menus can be set in System Configuration
-You will have to relog after changing skins to apply them
-All UI elements being expanded and improved, such as...
-Cross-world Linkshells will have 8 channels
-Enemy target HP Bar will now show health down to tenths of a percent (so you can see if you wiped at 1% or .1%)
-Party list info updated, including being able to see exact values of allied HP and MP
-Housing furnishing placement preview
-And more!

BATTLE SYSTEM CHANGES

Charged Action System: https://i.imgur.com/T1zPOKr.jpg
-Some actions will now charge continuously, charging to a cap
-These moves will no longer require you to use them as soon as they come off CD or risk losing DPS
-Includes MNK's Shoulder Tackle, NIN's Kassatsu, and more
-Some moves will stack more than others. Tooltips will tell you how many stacks are available

The MP and TP Systems: https://i.imgur.com/NQrtFom.jpg
-MP is capped and TP is eliminated
-Piety will now increase MP regen rate and is still only effective on Healers

Casting Interruption System: https://i.imgur.com/bJ7wP8h.jpg
-Player ability to interrupt enemy spell and ability casts being overhauled
-Enemy cast bars will now be highlighted and animated to indicate if they can be interrupted rather than player trial-and-error
-Tanks and Ranged DPS will receive new Role Actions specifically for this purpose

Speaking of Role Actions...
Removal of Role Action Customization: https://i.imgur.com/8sECpLq.jpg
-Role Actions are being changed from a customizable list to set actions per role
-Actions are automatically obtained on reaching the required level
-Number of available actions per role is being adjusted

Main Attributes and Materia: https://i.imgur.com/jnzL5YM.jpg
-Accessories will now give STR and VIT for tanks and VIT for everyone else
-No more Materia that gives Main Attribute increases. Existing materia will be made useless, existing gear will be improved/changed to compensate
-Weekly token gear and Savage accessories and belts will now have 2 materia slots each
((Note: It doesn't make sense to me that accessories will only give VIT for non-tanks, rather than STR/DEX/INT/MND respectively, especially considering the Materia change, but that's what they said.))

Pet System: 1. https://i.imgur.com/iOUrShM.jpg 2. https://i.imgur.com/Sha0lme.jpg
-No info other than what's in the screenshots

Additional Battle System Adjustments: 1. https://i.imgur.com/GaTeyWv.jpg 2. https://i.imgur.com/5OO0Ixb.jpg

REBALANCING PLAYER ROLES

Job Synergy: https://i.imgur.com/sXFgI53.jpg
-Effectiveness of synergies between certain jobs will be reduced
-Slashing, Blunt, and Piercing Resistance debuffs are being removed
-Other actions are being revised or removed
-Dancer's role as a buffer will be emphasized, but Dancer is not intended nor designed to be necessary in every comp
-The overall idea here is not to remove synergy entirely, but allow for more variety of party comps

Tank Role Jobs: 1. https://i.imgur.com/Js9JJuE.jpg 2. https://i.imgur.com/Y4qNwbg.jpg 3. https://i.imgur.com/sViMLWv.jpg
-Adjustments to account for MT and OT (all tanks will be viable in both roles)
-Intended to reduce parties disbanding because they were matched with two MTs or OTs
-Tanks will have buffs that can be applied to the party, OT will have buffs for the MT, these will be different for each class. Job effectiveness will boil down to player skill.
-Tanks no longer need to worry about sacrificing a damage rotation to use an enmity rotation

Healer Role Jobs: https://i.imgur.com/m7vnAPJ.jpg
WHM:
-Healing lilies will accumulate automatically/passively over time during combat.
-Will have more instant-cast heals to promote mobility and more time to cast other spells ((they didn't say if it was oGCD but it sounds like it))
-New Black Lilly that will enable use of a powerful offensive spell
SCH:
-Will have more healing spells to supplement their repertoire of shield spells and makeup for Pet actions becoming player actions
-Can summon Seraph
AST:
-Card effects are being changed; each card will apply “some sort of damage increase”
-Draw and Play are now separate; Draw recast time begins on the draw, not when putting the card on a player, in the sleeve, etc
-New ability to allow access of either Stance for a period of time (mid-combat stance swapping)

DPS Role Jobs: https://i.imgur.com/4XavEca.jpg
-More “traditional” designs concepts with appropriate mechanics
-MNK/DRG/NIN/SAM/BLM/RDM are largely unchanged in terms of core mechanics and general play style.
-MCH will be changed significantly
-BRD/SMN being partially reworked
MNK:
-Action to unlock 4th GL stack
-Action to maintain GL stacks during breaks in the action
DRG:
-Removed Heavy (?) Thrust (she kinda mumbles this, but this is the closest approximation to what is said. See 1:23:16 in the VOD to guess for yourself)
-Changed Mirage Dive activation conditions
-Jumps are quicker
SAM:
-Base mechanics are largely unchanged, changes are mostly to the “evolution” of the class
-Hagakure optimized to allow Midare Sesugekka to be activated “more smoothly”
NIN:
-Enmity-negating moves removed in response to the new enmity generation abilities of Tanks
-New high-level Ninjitsu
BLM:
-Yoshi's Main
-Only pre-existing class so far to have an actual gameplay demo to go along with the rundown
-Umbral Soul: Grants Umbral Ice and 1 Umbral Heart, requires Enochian and Umbral Ice to cast. Used to maintain Umbral Ice and Enochian between fights. ((Think Transference, but better))
-Xenoglossy: Instant cast. Unaspected damage with a potency of 750, requires Polyglot
-Blizzard III now costs 0 MP
-Despair: Cost 10,000 MP. Grants Astral Fire III. Deals fire damage with a potency of 380, requires Enochian and Astral Fire
-More instant-cast spells
-Casters no longer have Mana Shift
RDM:
-Like SAM, base mechanics are largely unchanged, mostly changes to the “evolution”
MCH:
-Redesigned to the point it's basically a new job. No more bullet/ammo gauge or Gauss Barrel
-New: Heat Gauge and Battery Gauge
-Now more of a “look at all my weapons” class instead of “this is my gun, my gun is amazing”
SMN:
-Ruin IV: Activates in response to your pet doing a certain action
-Egi summons are instant-cast
-Can now summon Phoenix, big-boy summon like Bahamut
-“No longer need to worry about generating Aetherflow before going in to combat.” ((Passive Aetherflow generation?))
BRD:
-No longer buffs party crit hit rate
-The Warden's Paean: Now a song, new effect in response to DoT crits
-New: Soulvoice Gauge, allows use of more powerful actions

Due to density of info, I'm not giving a rundown on Gunbreaker and Dancer. You'll have to watch the demos yourself at https://www.twitch.tv/videos/428913285
Gunbreaker starts at 1:00:47
Dancer at 1:45:30

SE at E3: https://i.imgur.com/u79nX0S.jpg