Pre-OTA, my Bluetooth headset (Jabra BT250V) had problems. Sometimes it would not give the voice prompt in response to pressing the headset button. Sometimes the "Please say a command" prompt came out of the phone speaker instead of the headset. A couple of times I had one-way audio (called party could not hear me) on the headset. Cycling Bluetooth in Settings fixed it.
Post-OTA, the headset works fine. No more problems of this type. That was my #1 problem pre-OTA so I am happy.
Pre-OTA I had one hang requiring a battery pull. Post-OTA none so far.
Camera of course looks a lot better. Not blue and I can now compare built-in with Camera360.
I noticed an anomaly with Email. I have two IMAP accounts set to Manual polling mode with Data Push disabled, i.e. only fetch email when I open the account. Pre-OTA, the phone respected that. The email would not update unless I opened the account or clicked Refresh.
Post-OTA, the phone sometimes decides to poll the Inbox on its own. It seems like if the Email app is in memory, it polls sometimes. I have access to one of the mail server's logfiles, and will try to figure out the pattern.
The first press on the Power button still does not always light the screen. I'm getting in the habit of using other methods (headset, volume buttons, open keyboard) to turn it on, and saving the power button for when it's needed (restarts.) There are too many threads on here about broken power buttons, and this phone needs to last two years.
This afternoon I put the phone in the case with the screen lit expecting it to go to sleep. 45 minutes later I took it out - phone was hot to the touch and battery was at 40%. Putting it away somehow started Barcode Scanner which kept both the screen and the camera on for all that time. Ouch. AndroSensor showed the battery at 114.8 degrees. I let it cool and charged it back up, and it seems fine.
Update: HDMI to a monitor worked, but the HDMI icon did not go away after I unplugged. If I clicked on the notification, nothing happened, but the icon stayed and the phone did not turn off the screen. I had to power cycle. Camera looks excellent now.