Fixes and Changes:
-Shift+Click on items will work correctly.[5]
-Labels for items will be added.[6]
-Redstone circuits not working after /time set x glitch going to be fixed in SMP.[7]
-User-placed leaf blocks won't decay.[8]
-Clouds won't go through buildings anymore.[9][10]
-Pressing F3 will no longer show numbers above the mobs heads.
-Rain and snow will now render faster.[11]
-Cloud movement syncs with the time.[12]
-Ghast attack sounds will be fixed in SMP.[13]
-Skeletons now hold full-size bows.[14] (found at 7:00)
-Skeleton arrows originate from about their eyes to the bow, instead of above the head.
-The snout on pigs will protrude from their head.[15]
-Pressing F+F3 will now alter render distance/fog.[16]
-Passive mobs will randomly flee if attacked by the player or other mobs (such as Wolves). [17]
-More Mob-To-Mob interactions. [18]
-Armor bar moved to above hearts, due to food bar.[19]
-Clay is now commonly found under shallow Water.
-Player to mob damage decreased by half a heart.

Features:
-Right clicking with a sword lets you parry.
-At least 9 new crafting recipes.[20]
-Stone Brick.[21]
-Stone Brick Slabs.[22]
-Stone Brick Stairs.[23][24]
-Brick Slabs.[22]
-Brick Stairs.[23][24]
-Fence Gates.[25] [26] (around 0:52)
-Glass Panes
-Iron Bars
-Melons
-Melon Seeds
-The ability to place pressure plates on fences.[12] (around 19:55 in)
-Different game modes.[27]
-Creative mode.[12] (around 3:10 in)
-Flying in Creative mode.[12][28]
-Able to change time quickly and easily.[12] (around 6:00 in) Note:Notch is in debug mode[12] (around 5:36 in)
-You will get unlimited resources in Creative mode.[12] (around 11:20 in)
-A new screen, the Unlimited Item Selection screen.[29]
-At least three new mobs.
-New Enderman mob.[30][31]
-They take damage from water.[12] (around 32:10 in)[28]
-They emit black smoke particles.[28]
-They will drop Ender Pearls.
-They open their mouth when hostile/looked at.
-New Silverfish mob.[12] (around 13:10 in)
-Very rare.[12] (around 13:10 in)
-Will spawn rarely when mining a block.
-New Cave Spider mob.[32]
-They spawn in Abandoned Mine Shafts.[33]
-Their attacks are venomous, and turn the player's health yellow upon being poisoned(will not kill you but will make you lose 4 health bars, if you are below 4 health bars then it will bring you down to heart).[34]
-Have a unique mob spawner.
-They are smaller than regular spiders.[32]
-Zombies drop a new item instead of feathers,[35][36] Rotten Flesh.[12] (around 11:40 in)
-New features in the terrain generator; things which will only appear in new worlds/chunks.[37]
-Optional[38] NPC Villages[39] with farms[40] and "town borders".[41][42]
-Possibility of players to "claim" land in villages.[43]
-Wells for villages.[44]
--Made of: Cobblestone, Mossy Cobblestone, Wooden Planks, Wood, Torches, Cobblestone Stairs, Gravel, Fence, Glass and/or Glass Panes, Ladders, Wooden Doors, Crops, Farmland, Water, Lava, Furnaces, Iron Bars, Black Wool, and Pressure Plates.[12] (around 3:50 - 4:30; 19:30 - 20:00)
-Contain "Smithies".[45]
Will spawn only on flat areas.[46]
-Underground Ravines including canyons on the surface and ledges to walk on.[47][48][49] (about 24:00 in)
-Strongholds,[50] consisting of 4 new blocks: Stone Brick, Mossy Stone Brick, Cracked Stone Brick, and Iron Bars.[51]
Abandoned Mine Shafts.[12] (around 13:55 in)[49] (about 25:55 in)
Naturally found Cobweb.[12] (around 13:55 in)
-Totally new, fractal-based[52] biome code.[53]
7 new biomes.[12] (around 24:25)
New "Mushroom biome".[54] which will include Huge Mushrooms, both brown and red.[55]
-Rivers flowing through/in between biomes.[56]
Ocean Biomes, that are deeper and larger than before.[57]
Mountain biomes.[12] (around 29:15)
-Swamp biome.[58]
Possibly new rainforest biomes.
Possible Volcanoes.[12] (around 22:00)
Larger Biomes.[59]
New combat Mechanics.[39]
Hold-to-charge bows.[60]
3 different charged states; takes less than 1 second to fully charge.[12] (around 5:05 in)
Fully charged bows causes the player to walk slower.[14] (around 5:40 in)
-Critical hits.[61]
When the player hits a mob while jumping.
When the bow is fully charged.
-Player blocking attack animation and hostile mob attack animations, possibly more player animations.[62][63]
-Block "stance".[28]
-New farming options, more interesting farming.[61][64][65]
-The Cocoa Bean tree Jeb was talking about could be implemented.[39]
-Plantable pumpkins and melons, each with a central stem that grows to max size and spawns a fruit next to it.[66]
-Melon Seeds.
-Pumpkin Seeds.
-New Food System.
-There is now a food meter.[67][68]
-Food no longer heals directly but indirectly.[67]
-If the food meter is above 80%, heals about every 5 seconds.[12] (around 31:00)
-Food will be stackable.[69][70][71]
-Food takes 1.6 seconds to consume.[67]
-There is now a food eating animation.[12][67][72] (around 5:30 in)
-5 new food items.[73]
--Cooked Chicken.[74]
--Raw Chicken.[75]
--Has a chance to "give you a disease".[76][77]
--Raw Beef.[71][78][79]
--Steak.[71][78][79]
--Melon Slices.[80]
-Cooked Porkchops have a different texture.[71]
New achievements.
-Kill a skeleton with an arrow at 50 meters.[81]
-Possibly attempting Shoot the Moon with an arrow.[82]
-Sprinting: By double pressing the forward button, the player will move faster.[83]
-Sprinting will be limitless, but will deplete your food bar.[84]
-Hitting a mob while sprinting sends them flying[85] about 8 blocks.[12] (around 7:50 in)
-Jumping while sprinting boosts the jump to a length of 4 blocks.[84][86]
-Sprinting makes particles come up from the ground.[87]
-While sprinting, The field of view will slightly increase.
-Glass Panes.[88]
-Can be mined and picked up without breaking.[89] (about 1:45 in)
-Possibly Spike blocks, Jeb initially considered Spike Pistons, but then pondered making a Spike block that can be pushed by the Sticky Piston.[90]
-Arrows will get stuck on mobs when they hit.[91]
-Vine blocks.[92]
-They will not be climbable.[93]
-Player can walk through them.[94]
-Improved chest model with a 3D lock and an open state/animation.[95]
-They are now slightly smaller than one full block.
-The ability to convert Creative worlds to Survival worlds ingame.[96]
-New uses of shears.
-Vine
-Tall Grass

Graphics / UI / Audio:
C418 mentioned new Minecraft music.[97]
HD Texture pack support (found in the pre-release)
New improved lighting — day/night cycles will not require chunk updates.[98] Lighting will be updated via a texture, whose coordinates are the block's sky light and block light levels.[99]
Warmer light from torches.[100]
Moonlight is blue.[12]
New texture for Moss Stone.[101]
Sliders for field of view and Brightness in video options.[102][103][104]
Redesigned HUD, including two new features, food and experience bars.[105]
Killing a mob gives you tiny flashing Experience Orbs that add to your experience.[12] (around 19:35)
New launcher.[106][107]
Possibly a web Applet launcher.[108]
A lot of new sounds and some changes, such as minecart sounds and shear sounds, also a change in the sound of rain.[109][110]
New bow sounds (including hits), new door sounds, big slimes sound, and walking skeletons sound more skeletony.[111]
New particle effects.[112]
Performing a critical hit on any mob will cause 'sparks' to fly.[12] (around 4:45 in)[49] (around 18:54 in)
Explosion particles are now shockwaves instead of smoke.[12] (about 21:54 in)
The ability to see the world seed when pressing F3.[113]
A new main menu background.[12] (around 2:10 minutes in)
The version in the main menu will be in the lower left, instead of the current upper left.[12] (around 2:10 minutes in)
Tiny stationary bubble particles can be seen when underwater.
Fog is now thicker and darker deep underground.
The void is now black and gives off particles.
Destroying boats and minecarts create particles.

Multiplayer:
Multiplayer server list.[114][115]
Improved server join screen: The server join screen will feature a list of servers.[116]
Player List - Press tab in multiplayer and player list comes up.[84][117]
The ability to allow moderators to enter creative mode in SMP.[118]

Modding:
Modding Support.[61]
Including easier changing of the max level (map) height.[119]
The terrain generation code is tidier.[120]