New Mobs.
Enderman
Silverfish
Cave Spiders

New Blocks
Stone Brick
Stone Brick Slabs
Stone Brick Stairs
Brick Slabs and Brick Stairs
Fence Gates
Glass Panes
Iron Bars
Melons

New Creative game mode.
New features in the terrain generator.

Optionally generated structures
NPC Villages
Strongholds
Abandoned Mine Shafts
Ravines

New, fractal-based biome code; added and removed some biomes while making all of them more vast than before.

Rivers flowing through/in between biomes.

Ocean Biomes, that are deeper and much more vast than before.

Mountain biome

Swamp

Snow in Taiga and Tundra biomes do not generate for technical reasons. They return in Beta 1.9.

New ocean floor; random mix of sand, dirt, and clay.
Because of this, clay is much more common.

New combat Mechanics.

Hold-to-charge bows.

Critical hits.

Players can parry with a sword by holding Right Mouse

Hostile mobs perform attack animations.

Mobs killed by players drop tiny flashing Experience
Orbs that add to your experience bar.

New Food System.

There is now a food meter.

Food no longer heals directly but indirectly: if the food meter is above 90%, heals about every 5 seconds.

All food (except Mushroom Stew) are now stackable.

Food takes 1.6 seconds to consume, accompanied with an animation.

5 new food items.
Melon Slices.
Raw Chicken.
Raw Beef.
Cooked Chicken.
Steak, which has Cooked Porkchop's old texture. Cooked Porkchops' new texture is a tan shade of the same sprite.
Eating any raw food or Rotten Flesh has a chance to give the player food poisoning which makes the Hunger bar decrease three times as fast.

New seeds for farming: pumpkin seeds and melon seeds that produce Pumpkins and Melons respectively.
A new achievement: "Kill a skeleton with an arrow at 50 meters".

Added Sprinting

Added Ender Pearl

Mob changes
Passive mobs will randomly flee if attacked by the player or other mobs (such as Wolves).
Zombies drop Rotten Flesh instead of Feathers.
The snout on pigs now protrude from their head.
Skeletons now hold full-size bows.
Player-to-mob damage decreased by half a heart.
Arrows that hit a mob visually "stick" into the mob rather than just disappear.
Skeleton arrows originate from about their eyes to the bow, instead of above the head.
Animals no longer despawn which makes it possible to capture them.

Shears can now collect Tall Grass and the new Vine

New improved lighting

Day/night cycles no longer require chunk updates and is a smooth transition

The lighting on a block is given a tint based on the most prominent source of light
Redish from Non-sunlight light sources
Blue from Moonlight
Total darkness keeps the same black tint
Sunlight gives the same white tint
Non-sky based light now gives a very subtle 'flicker'.

New Mojang logo splash screen

Main Menu/Options changes

The Main Menu's background is now an animated scene.

The version tag is now displayed on the bottom-left rather than the top-left

New sliders for Field of View and Brightness
4 new entries in control list

"Attack", "Use Item", and "Pick Block" can now be remapped.

New texture for Moss Stone to match Cobblestone's.

Improved sunrise and sunset.

Clouds change color during sunrise and sunset to match the sky color.

Horizon, specifically haze changes color more vividly during sunset and sunrise.

New particle effects.

Performing a critical hit on any mob will cause 'sparks' to fly.

Explosion particles are now shockwaves instead of smoke.

Tiny stationary bubble particles can be seen when underwater.

Fog is now thicker and darker deep underground, and gives off particles. Due to this, the void appears black.

User-placed leaf blocks no longer decay.

Cloud height raised to the top of the map, so clouds can no longer phase through blocks.

Cloud movement syncs with the game's time.

Rain and snow both render faster

Armor bar moved to above hearts, due to food bar.

Both Wooden and Stone pressure plates can now be placed on fences.

Improved chest model with a 3D lock.

Players with the OP position on a server can switch back and forth between survival and creative mode.[2]

The game's coding now allows for mods to more easily change the(map) height.

Holding the left mouse button with a weapon will now only swing once.

Holding the right mouse button to place blocks is slightly slower than before.

Bug Fixes:

Destroying boats and minecarts now creates particles.
Ghast attack sounds are fixed in SMP.
The Far Lands had been removed; there is now only ocean.

They hope to release it in the next week so hopefully it will be and it includes creative mode XD

Thanks to goldendiamonds for all the info on this topic credit to him XD

post what you think of the next update

1.7.3 update info :


Fix for a crash with pistons at the edge of the world
Fix for a crash due to a thread safety issue usually caused by pistons
Fix for issue with operating pistons on chunk boundaries
Fix for a rendering flicker with active pistons
Fix for rendering slowdown due to lighting issues
Fix for rain going through blocks (raining indoors)
Fix for Marketplace not launching when unlocking skin pack after selecting a locked skin in the trial version of the skin pack
Fix for bug allowing locked skins to be selected if they are beside a free skin
Fix for misaligned player scores when viewed under the "My Score" leaderboard filter
Fix for the constant button press sounds when rotating a character in the skin select screen
Fix for the constant sound effect played on the sign text entry
Fix for thunder not being audible
Fix for third person front view not displaying fire.