This is going to be a quick post just to briefly talk about my experience with Android 12. To be honest, I was completely shocked when my phone updated. Android 12 is slicker than a Slip 'N Slide covered in baby oil.
I do not say this lightly, especially since I have a 2-year old phone (Pixel 3a XL) that was not even the top of its class when it was released. The performance increase with Android 12 is truly night and day. I went from having a noticeably aging phone that was starting to get sluggish to one that zips through menus, drawers, windows and anything else like I just shoved an RTX 3080 into it. OK, I exaggerate, but it really is a nice experience.
Other features are nice too, such as an revamped UI with useful improvements to the notification area and the auto theming. They have also fully embraced rounded corners, which is the kind of useless upgrade I typically expect from phone OS devs, but the performance optimization more than makes up for it.
That is all. This is not a full review, but I just wanted to share my impressions. If you have a phone that will not be upgraded to Android 12, I feel sorry for you. Perhaps it might be time to explore custom ROMs.