Some cool things MoP is going to have:
1. Cross Realm Zones
2. Random NPC armor sets
3. Gorrosh Hellscream is going to be a final raid boss (Thrall comes back, or someone else?)
4. More PVE content than any other expansion (Challenge mode, scenarios, huge raids (16 raid bosses), two world bosses, NINE new dungeons at launch, two dungeon revamps...)
5. Lots of PvP content. Two new battlegrounds, completely original gametypes. One is similiar to payload in TF2, the other one you try to hold a ball that deals damage to you, but the team that holds the ball for the longest wins. A new arena. Return of world pvp zones.
6. A new mechanic where you can upgrade your items with valor points
7. Pokemon minigame.
8. A black market auction house where you can buy rare items for ludicrously high prices.
9. Lots of class changes, talent system overhaul with the goal of eliminating cookie cutter specs, Warlocks have been completely overhauled, Druids now have four specs (Balance, Restoration, Guardian, and Feral.)
10. Professions have been given tons of additions, inscription now makes shoulder enchants, cooking now has four different specializations, archaeology has been given a bunch of new sites, and items, plus new things to do with archaeology to make it less boring.
11. More reasons to level an alt because MoP integrates account wide progress, achievements are now account wide, heirlooms can be transferred to any character on your account, mounts are shared across all of your characters.
