Screw World Celebration. Literally everything about it is bad.
It's ugly.
It has obnoxious, low quality shows/DJ music, which gives it the distinctive honor of being the only land that actively makes the areas around it worse because they're so darned loud.
CommuniCore Hall, in all its high school cafeteria glory.
The Mickey and friends meet where the queue is outside even though it's still within the building's rectangle footprint and all they had to do was build one more half of a wall (and a small section of half a wall for the entrance) with a couple of doors and it would be enclosed and air conditioned. It's a level of stupid you need to go out of your way to do. Who the hell benefits from that building being designed the way it is?
(Festival Favorites, part of a brand new building, is outside, too. Again, benefiting absolutely no one.)
The name. Making everything match World Showcase is a failure of elementary school English (it is a showcase of the world, not the world of showcases; copying it makes no sense) and "World Celebration" is in the running with "World Discovery" for most vague, useless name they possibly could have come up with.
Even the lights are too darned hard for Disney to manage as they keep breaking.
Then they decided this utterly charmless, aimless, painful (literally, for those standing in the outdoor line) "land" was the perfect place to put a Walt Disney statue to empashsize how proud he would be of them. And slap old Epcot stuff on the walls to remind you what you lost.
Again, screw World Celebration.