I upgraded to iOS8 from 7 and the message app is different when I delete messages. in iOS 7 when you delete a message, the conversation order goes back to the last existing text. for example if you delete some text in an existing conversation, this conversation will be fall behind newer text you sent after the last existing text you have. for iOS8 however, after I deleted texts from a recent conversation and the last existing text in that convo was something i sent two weeks ago, the convo is still all the way on top when i have other convo from minutes ago. I don't know if I explained this clear enough, it is supposed to be like this, it doesn't make any sense. in iOS8 the text conversation order isn't based on the last existing text time stamp, but instead is using the actual order convo order even if the text doesnt exist anymore. Maybe this explains it better. This is a crucial issue and I have not seen anyone address it. I hope it gets fixed soon.