Last night I read a lot of people's comments about these type of issues and I have been posting I noticed some but that it's in general pretty okay. So I spent about a full hour documenting it with feedback app.
There are quite a few more on the iPad than I have on the iPhone, and some of those I can reproduce, while others seem to be depending on screen orientation or the app in use.
The log files when something goes wrong are pretty small, hardly useful, or actually pretty big showing break points in the framework reporting back all sorts of stuff.
The orientation bug is my biggest issue, and has been there since the first public beta. There are other apps in the background causing it to 'lock' when it shouldn't. I can't tell if they are using older framework, are one of those incompatible apps, or just exported as universal apps. I haven't been able to really narrow it down.
The facetime bugs I had people report I have been able to test as well. I have an iPad Air 2 that we left on for 6, 12, and eventually 24 hours. And almost right on the money at 24 hours the sound starts cutting off on the other end. They can hear me, and I can't hear them. They have to unplug and plug back in to get the driver to wake up again.
Additionally, after about 6 hours the screen suddenly starts deciding randomly that it needs to darken up, causing it to 'freeze'. On video call this means you have to keep the device moving and active to avoid that. It thinks it has to safe power. Even though it's connected to a wall socket, and it has been fine the first 6 hours. now of course, people might not really facetime that long constantly, but i do. With my bad eyes it's how i stay in touch with friends, sorta like a digital room mate. Plus, this time, pure testing.
The widgets have their own sort of UI issues, the ones reported in this thread are quite consistent. Well, they break more frequently visually than they should. The UI lag it causes shows the events are starting too quick and then lag when they try to update cache or whatever it is. If that happens in the middle of a touch action like a swipe, it hangs on the edge of the screen and becomes unresponsive. On the phone this doesn't happen, to me, but it does in a way, it just doesn't show anything and after a very quick pause it continues to slide and widgets appear. Happens once a day-ish.
My feedback app is updated with logs and screenshots and much more detailed explanations. But the first 12 issues were easy too add. Shame. So beta-feeling-ish. A lot of the feedback reports from ios9 and ios10 beta period still are unresolved in 10.1 it seems, I re-submitted them for 10.1, with updated information.
It is a lot of work and very time consuming to read comments and figure things out, and try to understand how it all works and what not. I am clearly amateur, but I want a good OS, but I hope it is all worth it. And more people do it.