I encountered the following failures since the launch of the service:
- iMessages on my Mac have always been delivered several, up to 10 minutes later than on my iPhone
- Sending iMessages on the Mac failed at first in 90% of the cases; I had to resend them prior to Mavericks
- Yesterday the activation of my phone number suddenly disappeared from both my Mac and my iPhone
- Since yesterday the delivery of the iMessages has been unreliable: I haven't received Messages which are shown "Delivered" at the peers' end and vice-versa.
(Being an iPhone developer, I reported all the issues.)
Is it a bug in iOS 6 and/or 7?
Apple rarely admits failures.
Is it an infrastructure issue?
Not according to their systems status page.
Is it because of solare flares?
Fact is that compared to other messaging services such as Viber, Skype, Facebook or GTalk Apple's iMessages is by far the worst in terms of reliability! This is not the quality I'm used to…