MOApp blog:

Core Data doesn’t work. Your own solutions built on top of iCloud don’t work, thus you finally start to rewrite your Apps to all use a document based approach – because it seems to work for document based Apps. At least that’s what they tell you.

Until you realize it does not.

Just another tale of how terrible it is for developers attempting to work with iCloud – and Core Data specifically

It hasn’t worked for over two years now and I am the one feeling ashamed every time I have to give the same ridiculous answer why I still haven’t finished my iOS Apps.

Ouch.