I did notice a strange behavior since iOS 7 installed.
I have the "send as SMS" switch turned to OFF in settings, but if I send an iMessage in a poor coverage area and DURING THE SENDING PROCESS (that could last a few seconds) data connection is lost, the iMessage is automatically changed in SMS , switching from blue to green, and sent as an SMS ....
It wasn't that way with iOS 6 (unless you did press "try again as SMS" button).
I have the "send as SMS" switch turned to OFF in settings, but if I send an iMessage in a poor coverage area and DURING THE SENDING PROCESS (that could last a few seconds) data connection is lost, the iMessage is automatically changed in SMS , switching from blue to green, and sent as an SMS ....
It wasn't that way with iOS 6 (unless you did press "try again as SMS" button).