Here are a list of already gathered undocumented changes and failure in 1.2.3 patch. I suggest every1 add something he noticed which is not in this list so every1 will be aware.
(link to source:
http://www.reddit.com/r/elderscrollsonline/comments/290ksh/changes_not_listed_in_patch_notes/)
The toggled free mouse has a new appearance.
A bent double-sided arrow appears in the character select screen to let you know you can rotate the character.
When a friend logs in, it now tells you what character they logged in to.
Items which previously had the "lock symbol" for enchantments now display a quote instead: "This enchantment cannot be replaced.".
Default prices are no longer applied when listing an item for sale in the guild store (all prices are 0 until you change them).
One of the Jazbay Grapes provisioning item is now named Piquant Jazbay Grapes.
Horse sounds have changed again to be more quiet.
PvP Assault skill Rapid Maneuver no longer affects horse speed.
Materials now list what level range they are used for.
Staffs have a new sheathing sound.
(unconfirmed) Nord racial changed from + armor to % damage reduction
(unconfirmed) Negative effects to alchemy potions have their magnitude increased
Map (M) now has a sound when you zoom in\out. Sounds like gears
Night's Silence set replaced the 3 trait bonus. It is not 40% health regen while sneaking, it is now 220% extra sneaking movement speed.
The Twighlight Matriarch is graphically enhanced
The minimum distance for opening containers has been increased
All large storage containers, trunks, cabinets, etc, may also now drop white quality items to that region's level
Magicka Furnace 5 piece set is 15% magicka regeneration with 30 second cooldown.
Official patch notes said the "Command Pet" option is now 'Y', but didn't mention it can be changed in keybinds -> Combat.
Raw Jute has been made more colorful, and noticeable, as well as some orange color added to its leaves
Enemy NPCs are able to CC break now, same as a player is able to. Also includes the after-effect of 3 second CC immunity.
The sound that plays when you try to use a skill or dodge roll when you don't have enough magicka or stamina is much louder
Slight edit to Achievements tab
New sounds to the death recap screen
Mundus Stones now give you a prompt with a detailed description of their effects before you commit to activating them.