Minecraft wiki entry for The_Update_that_Changed_the_World, associated text: Improvements to existing biomes
Ocean biomes are smaller and take up less of the world
Treasures can be caught by fishing
Achievements and statistics are now per world/server
Fog is less noticeable on lower render distances
Re-added pre-1.6.1 boat controls
Weighted pressure plates are no longer limited to items
Unbreaking from enchantment tables is no longer limited to tools
Hitting a mob with a sword while it is flashing red and inflicting no damage, as a result, does not decrease the durability of the sword
Witches now spawn outside of Witch Huts
Render Distance and Max Framerate are now sliders
Cave Generation was tweaked, making caves less dense and interconnected.[2]
The server list can now be refreshed by pressing F5
Achievements earned are announced to everyone
When a mob or player takes fall damage, particles appear