Level cap increased, new race, new zones, new quests
a far better experience for newbies than the "old norrath" Bigger badder mobs, oh and did I mention the new lvl 60 cap? Total addicts heaven.
Once Kunark opened, I rarely went back to the old zones, only to go to guild meetings, or Plane raids, or do epic quest help for people or maybe farm stuff.
But for real XP or loot, Kunark is where it is at. The addition or more high lvl outdoor zones for some soloing also helped out.