Updated last night. It's nothing special. Don't notice any difference in how the phone runs. I didn't have any of the bugs they squashed.
I had one that was not noted bit was fixed. If you long-pressed the Do Not Disturb control in the control center and choose "until tomorrow morning" (or "until this evening" if you do it during the day), it would not actually turn on DND. This was fixed with 14.4. It's rare when I do this, but I am happy to see bugs fixed.
The new feature in settings that shows the Bluetooth device type is just ok.
I like it for two reasons.
1. I can now say that the BT in my car is actually car audio, which automatically puts my phone in Do Not Disturb While Driving. Prior to this it was considered a speaker for some reason.
2. This allows people to set devices as "speakers" so that people who are having issues with the phone automatically reducing volume per time have that prevented - this does not happen when a BT device is listed as a speaker.