Or I'll investigate this update and tell before you can!
What I've found so far (Testing server): UI improvements/changes. All sorts of menu changes. Will expound after further investigation.
Menus: Pressing exit brings you to an over-menu, containing Character Menu and Game Options subsections. Looks much prettier than before over-all with a white/grey/black theme and nice rounded buttons and fonts in a rocky-looking boundless-themed border.
Character Menu: Inventory, Character, Objectives and Worlds buttons, each leading to their own menus.
Inventory: Typical inventory with "Hand Craft" and "Friends" tabs.
Character: Contains "Profile" and "Skills" tabs.
Profile: Has "Overview" and "Character Attributes" sub-menus.
Overview: "Core Attributes" and "Resistances" expandable tabs!
Core Attributes: Lists quantitized Health and Stamina along with new stats, Vitality/Power/Control
/Dexterity and Agility/Intelligence/Luck/Energy. It also has sub-stats for Modifiers,
Damage Modifier/Drop Rate Modifier/Status Effect Duration Modifier/Healing Modifier/
Action Speed Modifier/Block Speed Place Modifier, as well as sub-stats for Building Range/
Global Armour/Walk Speed/Jump Height.
Resistances: Lists resistances, Self/Physical/Melee/Bashing/Impact/Scraping/Healing/Burn/Chill/
Character Attributes: Pretty much identical to previously.
Objectives: Mine is greyed-out so far, so no info at this time.
Worlds: Contains tabs for Locations, Beacons, Settlements and Worlds. Very nice!
Game Options: Pretty similar to before, has Return to Sanctum, Change Character Model, Reset Controls to
Defaults, Setting and Quit options. I will add that the "Settings" sub-tabs and menus are prettied up to the new
Non-functionality of menus if you attempt to swap left and right mouse buttons is still an issue.