To sum up MOP for me:
-The lanscape and architechture
-Much of the raid armor
-Raid dungeons. Fun and don't drag out for hours.
-And lots of general gameplay improvements
-Those horde monkey-people
-5-man dungeons in Pandaria, especially the Brewery. Not to keen on that extremely melee-unfriendly insect/wall place either.
-Mobs. The mogu are decent enemies, but I hate the monkey-people, fish jerks, monster-rabbits, and the sha creatures, and those silly beermonsters/waterelementals. The lizardpeeps, MOP-taurens and the insects are also ...ok.
-Too few weapon models. There is like 1 polearm, 1-2 for twohanders and 1-handers. Never anything unique.
-Too few high level weapons. I don't care about a million rings, boots, bracers or necklaces, give me some interesting.
-NPCs. Lots of different panda-factions, but I haven't really felt an interest in their story at all.
-Lore. I was interested in what was happening in the world, but...now nothing is happening part from the short scenarios.