I have read about these issues plaguing people. It is strange because whenever I have roamed overseas or have disabled data for whatever reason. People still can text me, albeit I am sure there is a delay between when they hit send and when I got the message.

Friends of mine have moved from iPhone to Android, when I send them a message it tries with iMessage - and I get the message failure exclamation mark. It then resends as a text and doesn't try iMessage again for some time. Haven't really had the black hole experience yet...