Drew Schuster on another unreliable Apple Internet service, iMessage:
OK, so sending a text and claiming it failed isn’t that bad. What would be really bad is if a “Delivered” text was never actually received. That happens too. All the time. I sent my dad an iMessage yesterday that he never received, even though my phone claimed that it had been delivered. He handed me his phone later that day to show that he never got it. I tried turning off wi-fi, data, killing the messages application, and restarting the phone, and was still unable to receive that text. That is unacceptable given the simple requirements of a messaging system.
-NuncaMind blog, December 28, 2011