For me, always on display has been the single biggest improvement to quality of life relative to my phone or any gadget since Face ID. For most of the hours of the day, my phone is on my desk next to me and not in my pocket. Instead of having to tap it or press a button once in a while -- a necessary practice for over 15 years -- now I merely glance at it to check the time, weather, and notifications. I don't even have a clock in my room anymore. And if there are not notifications needing my attention, I don't have to pick it up. It has actually let me use my phone less, or at least more on my terms.
There are also smaller scenarios where it comes into play. For example, when I sign into a web site on my desktop and it sends a code to my phone number or email, I don't have to rush to look at my phone and remember the code before the screen turns off. The code stays on the screen and I can take my time. (Yes, I choose some notifications to display preview while unlocked, where there's never a privacy issue. They require unlock to see the whole message or use the app anyway.)
Any battery hit is more than worth it. Why? Because the phone is using battery to do what I have the phone for in the first place. But my battery life is fine with it on. Also, putting the phone on low power mode automatically turns on always on display. So that's just a toggle away in the control center. It is also available as a filter in focus mode, so for example, if you are in a situation where you are with a lot of people and would like the screen to stay off on the table, just add that to your do not disturb or a custom focus.
