With the pre-expansion content update, players will experience a changed landscape in both Kalimdor and the Eastern Kingdoms. Players will be able to embark on new quests from level 1-60 in these transformed territories as well as begin their journey as one of the new goblin or worgen races.
In the wake of Deathwing’s devastation, adventurers will be summoned to embark on new quests from levels 1 to 60 in these transformed territories — and with so much new content to be found on these two continents, many original quests will no longer be available after the shattering occurs. These quests will automatically be removed from your quest log, while any quests you’ve accepted that still exist in Azeroth will remain in your log.
For those who are working through the Loremaster achievements, if you’ve already completed Loremaster of Eastern Kingdoms or Loremaster of Kalimdor, you will not lose your achievements. However, if you’ve made progress toward these achievements without yet completing them, be aware that any quests that are removed from the game will no longer count toward your progress, so you may see your achievement quest counter drop. If you’re close to earning either of these achievements, we strongly suggest you finish them with great haste, as Deathwing’s return is imminent.
In addition, the Loremaster achievements are being redesigned slightly to make them easier to track. Rather than having players complete a huge number of quests throughout a single continent, the criteria will change so that you will instead need to complete a set number of quests in each zone. Once you’ve earned the achievements for each listed zone on a continent, you will then be awarded the Loremaster achievement for that continent. For those who do have Loremaster of Kalimdor or Eastern Kingdoms completed already, you can still go back and get the new achievements for questing in individual zones on those continents.
Please also note that all exploration achievements are now account wide. If you already have the achievements, you should see them on first login, if you have made progress on several different characters, you will need to log into those characters to have the total reflected on your account.
Players can also enjoy an increased leveling rate through the Burning Crusade and Wrath of the Lich King content.
Source: news.blizzard.com