Some quests were offered while you still had one of their part quests open, and then said "quest failed". They now wait until the part quest is done, and the message tells you what to do.
The Alfheim weapon merchant now sells weapons for levels 24 to 33 instead of beginner weapons.
Fell through the floor on a field? After 2 seconds under the ground the game now puts you back on your last spot.
Searching the market by rank shows results again, and deleting an item from the equipment window now gives a clear answer.
The world map (M) now has pictures for Prontera Culvert, Forest of Echoes and Blue Echo. Your head turns to what you click while riding a Peco Peco. The stun skills' tooltips explain that the target's VIT, LUK and level lower the chance. Switching between windows is safer.
Start the launcher to get the update.