Minecraft Pocket Edition/Bedrock 1.12.0.2 BETA Released!

New Features:

Item instance IDs can now be synchronized between clients and servers
Added auto complete to command blocks
Added spawnRadius gamerule
players can specify in their worlds called spawnRadius. The concept was adapted from how Java Edition implemented it. It allows players to specify a number between 0 and 32 to create an allowed area for spawning to take place. So a spawn radius of 27 is a larger circle than a radius of 12. Players then will spawn in a random location in that radius.
Enabled content logging on Bedrock Dedicated Server
Added a delay option to command blocks
A delay can be added to the command block using the new field. The ticks for this delay are Redstone ticks.

For Map Makers and Add-On Creators:

New items can be added using Add-Ons
Mob events can now be enabled and disabled in world templates
Animations and particles can be added without being linked to entities
Inventory, armor, and hand containers can be adapted through scripting
Sound effects can now be triggered by animation events
Added new executeCommand to the Scripting API
Added Scripting events for interaction with items, for example:
Item picked up
Item dropped
Carried item changed
Added One-shot animation support, allowing the ability to execute a single animation on an entity
Particle emitters can now trigger Scripting Events
Updated documentation of Actor Events, to document client-side usage of actor events in resource packs
Add Block components now use JSON schemas
Created a screen to view content log errors
The log screen can be opened using Ctrl+H, or by going to Settings→Profile
Added code to allow static validation scripts to be run locally
Custom blocks can now be added through Scripting
This is currently still a 'work in progress' feature, and more functionality will be added in future updates.
Custom blocks can currently only be added through additional JSON scripting
Custom blocks can only be placed with slash commands

Added new Data-Driven Particles:

Llama Spit
Large Explosions
Coloured Flames
Redstone Dust
Falling Dust
Lava
Enchanting Table
Conduit

Added new Data Driven Animations:

Wolves
Fang Attack
Arrows
Shulker Bullets
Bows
Water

Updated Documentation to include a Breaking Changes section

Item API V0
Basic item related events have been exposed to the Scripting API. This includes:
actor_acquired_item
actor_carried_item_changed
actor_dropped_item
actor_use_item
actor_equipped_armor
Inventory API V0
Basic inventory events have been exposed to the Scripting API. This includes:
inventory_container
armor_container
hand_container (note that the hand container will get you both the main hand and offhand)
hotbar_container
Block API V0
New block events and two new APIs have been included to query for blocks. This includes:
APIs
getBlock(Ticking Area, x, y, z)
getBlock(Ticking Area, PositionObject)
getBlocks(Ticking Area, x min, y min, z min, x max, y max, z max)
getBlocks(Ticking Area, Minimum PositionObject, Maximum PositionObject)
Events
block_destruction_started
block_destruction_stopped
piston_moved_block
player_destroyed_block
player_placed_block
executeCommand API
Allows the Scripting API to get the result of a slash command
Event Data API
Allows Creators to create event data, register and pass it to the event function.
Updated Demo Packs

Fixes:

Crashes/Performance
Fixed several crashes that could occur during gameplay
Improved chunk loading performance in multiplayer
Further improvements to performance when using selectors with commands
Fixed a crash that could occur when switching players on Xbox
Cached resource packs no longer cause lag on Nintendo Switch (MCPE-36976)
Fixed a crash that could occur when launching the game on some Windows 10 devices
Fixed a crash that could occur when certain interactive blocks (e.g. beds, chests, furnaces) are loading in when joining a Realm.
Fixed a crash that could occur when engaging in a fight with an Elder Guardian in an Ocean Monument
Fixed a crash that could occur when throwing a Trident with Loyalty enchantment
Fixed a crash that could sometimes occur when exiting the game

General

Player permissions now apply correctly when more than one operator tries to adjust them
Arrows that are shot into blocks keep their position when reloading the world
Area of Effect clouds no longer try to spawn excessive numbers of particles when time of day is changed (MCPE-39595)
Marketplace resource packs are now immediately applied after downloading in the world edit menu (MCPE-33121)
The 'Always Day' toggle now correctly animates and shows the correct setting (MCPE-43304)
Flowing water is no longer left behind after flowing over string (MCPE-36343)
After the fishing_hook is killed by command the player can now cast the hook again without having to right click twice
The screen reader prompt no longer appears every time the player adjusts the network settings on Nintendo Switch
Removed an unnecessary Xbox Live sign-in notification

Gameplay

Marketplace offers page can now show more than 25 items
Items that are split between slots in the Villager trade window still count as a total trade amount
Blocks can once again be placed on unlit Redstone Ore (MCPE-44305)
World settings now sync correctly between different Xbox devices
Only players who fought in a Raid see and receive the Hero effect in Realms now
Bells now ring when hit with splash and lingering potions
Mob spawners now only spawn mobs if the light level is below 7 (MCPE-42427)
Cocoa beans now break and drop when pushed by pistons (MCPE-41868)
Fixed several related issues with End Gateway portals. These should now teleport the player to the correct safe location when used (MCPE-43176, MCPE-43177, MCPE-19699)
Efficiency Pickaxes now break Packed Ice at a faster rate (MCPE-23648)
Players that are being healed can still be knocked back by TNT
Villagers now keep their job when cured (MCPE-42348)
The Grindstone now correctly combines and repairs two damaged items
You can now interact with blocks with a charged crossbow on touch devices
The Bad Omen effect is now only received when killing a Pillager Captain, and not when dealing non-fatal damage with a bow or damage potion
Fixed various scenarios where certain blocks couldn't be placed until the game was restarted

World Generation

Fixed a bug on Dedicated servers and Realms which could cause the wrong block types to generate
Tweaked the number of job sites in villages

Mobs

Cured Villagers now keep their jobs
Vindicators can now path correctly over carpet during Raids
The Wither no longer plays its spawning animation when reloading a world (MCPE-32415)
Mobs will no longer path-find over Brewing Stands
Added sound to indicate when a Villager does not want to trade (during a Raid, for instance)
Pillager Captains now drop Banners correctly even if the world is reloaded
Mobs will now spawn on double slabs (MCPE-30765)
Re-added Zombie Villager sounds
Mobs now longer get stuck when pathfinding on ladders (MCPE-43034)
Added new Wandering Trader sounds
Converting a normal Pillager to a Captain with tag commands now displays the banner correctly
Evoker no longer moves too fast in "move to village" goal
Villagers that are actively trading with players will no longer run and hide if the raid bell rings
Clerics can now correctly pathfind to their jobsites

Blocks

Scaffolding can no longer be placed on Conduit blocks (this matches Java now)
The Bell now swings towards a player when it is hit (matching Java) (MCPE-42469)

Items

Dropped items no longer prevent Mine Carts from being placed on Rails
Empty glass bottles will now stack correctly when removed from brewing stands (MCPE-42175)
Shields no longer appear too bright in item frames (MCPE-41222)
Fixed Sea Grass texture brightness (MCPE-34795)
Barrel item is now in proper place in creative inventory (MCPE-43946)

Graphical

Fixed a z-fighting texture issue on some Villager skins
Corrected the position of leads on Wolves
Noteblock particles now correctly correspond to the notes played
Fixed missing Zombie Villager skin
Farmland now has the correct side and bottom texture (MCPE-42746)
Fixed door and trapdoor texture issues (MCPE-43173)
Dyed leather horse armour colour no longer effects other horse armour (MCPE-43230)

User Interface

Added controller tooltips for Lectern UI
Adjusted Cartography UI to fit Android screens when using Classic UI
Villager trading UI no longer opens and closes if the player is standing too far away
Added lectern UI controller tooltip

Add-Ons and Script Engine

Fixed a scripting bug that could cause the player to float
Pickblock (middle click) now works correctly on non-vanilla entities that have been added using add-ons (MCPE-38205)
ScriptAttackComponent and ScriptCollisionBoxComponent now correctly retrieve updated data
Functions ran on a game loop now use an origin which has Game Master permissions, not Owner permissions
Added a new constructor parameter to the ServerCommandOrigin so that the Function Manager can create an instance with upgraded permissions.

https://www.youtube.com/watch?v=kW8tDhvey_8

Source: https://feedback.minecraft.net/hc/en-us/articles/360027059411