The release of Mists of Pandaria was a reason for players that quitted before to return to the game and for the players that kept their subscription, something fresh to play considering that the game lacked new content for months.
From the point of view of an Alliance player, the start in Jade Forest was amazing with those helicopters, but shortly, the quests from the first leveling area were resumed to kill x mobs and gather x resources or items.
World of Warcraft has been like this for years, that’s why some players hate leveling since there is no steady story and progression but mostly because of these quests. There are some quests with different gameplay elements but only in Jade Forest, moving to Valley of the Four Winds, these kind of quests will become very rare.
Each zone has some final quest that concludes with the zone but overall players will lack the motivation to finish it.
How to gain XP except questing? You can go into normal dungeons and grind there with other 4 players or do battlegrounds. Battlegrounds are not very fun at the moment because there is no PVP gear and a player won’t be able to show his skills.
Blizzard should reduce the leveling to 4 or 3 levels cap for expansions as 5 seems to be too much.