Ever since upgrading to iOS 9.0.2, there are some people who I just can't message any more. And not all of them are iOS people (the documented bug is for people running earlier than iOS 9.0.2, which is silly too, but) --some of them are Android.
I try and send, message is green, and within less than half a second "Message could not be delivered". Rebooted phone, same issue. Turned off iMessage to force texting - no fix. This is impacting my ability to work, as this is a work device. It's extremely frustrating, and it's a show-stopper of a bug, not just something annoying. There are times when I don't have reception for a cell conversation but a text or an iMessage would work; yep, not gonna work.
I am enrolling in the beta program just in the hope that 9.1 beta 5 (released 10/12) might resolve my issues. This is probably foolhardy; if a public release causes the issue, how likely is a beta release from Apple to be more stable or bug-free? But, I have work I need to do, and until there's an official fix, I have to hope that maybe they addressed it in the most recent beta.
My first iPhone is an iPhone 6 (I've had smartphones since Kyocera was making PalmOS phones in the early 2000s) with many different operating systems, and this is by FAR the most disappointing smartphone of the ten smartphones I've had, with more bugs and problems. If my company hadn't standardized on these, there is no way I'd choose this product --and I work in IT. The hardware is just fine, but the software has been disappointing to say the least.