Well, there's no reason why player created levels can't have some sort of story. You can give 'characters' speech bubbles, and have they say what you like, I believe. I mean, it's all text and no actual sound, but you get the idea.
I'll certainly be giving my levels stories.
Don't expect anything deep, though. I mean, it's a 2D platformer. 2D platformers don't really need deep stories, though, do they?
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Anyways:
Pros:
-- Up to 4 players on a single PS3.
-- You can do pure co-op, or you can do 'co-op-etition' (where you have to work together to complete the level, but you're in competition to get the most points),
-- Comes with a bunch of mini games too, which look like plenty of fun.
-- Level creator + sharing = loads of content to play.
Cons:
-- Penis levels.
-- Can't upload your own textures from your hard drive. (Although, MM have said they'll consider patching it in after release.)
