OK, so...I saw this article this morning:
Anandtech iPhone SE Retested
TLDR version: Anandtech's initial review panned the new SE's camera; they felt it took poor photos. Apple took a look and agreed, and shipped Anandtech a new SE, and they retested and found the same thing everyone else found: a really good camera.
So, assuming that they had a defective unit, as they opine in the piece it's unlikely that just one unit was defective. Perhaps it was just one batch, but it was unlikely to be just one phone. Now I'm wondering if mine was really all that better than my previous SE's. When I tested them against each other the day my new one arrived, the lighting conditions were PERFECT: bright sunny day, and lots of good indirect light inside. I only took a couple of photos; they were almost identical, and I just chalked it up to it being such a good day that ANY camera would nail it.
I have since passed along my old SE to another user, but it occurred to me that my partner still had HER old SE. She would not be worried about ANY of this, so I appreciate that she didn't roll her eyes as I asked to borrow her phone for a camera test. Today's lighting is a lot less bright: it's completely overcast, the indoor light today is significantly dimmer. I went around taking various photos with both cameras.
The challenge is, I don't know HOW MUCH BETTER I should expect the new SE photos to be. I know how much better my DSLR was than my old SE; should the new SE be closer to that, or closer to the old SE? What should I be looking at? Here is what I found (again, based on my own judgement, which may be less fine-tuned than others'!):
--The color seemed better, less muddy, on the new camera.
--The new camera did a much better job of pulling detail out of a backlit background.
--When I zoomed in, and looked very closely, the sharpness of the photos looked VERY VERY CLOSE. In fact, if you told me that, throwing out other aspects, the sharpness was exactly the same between cameras I wouldn't dispute it. BUT...you don't generally look at photos like that, and when you DO add back in the other aspects, the photos at a more casual look do appear sharper because the muddiness of the colors is much less.
That was what I saw when looking at it on my phone screen (the new SE's screen). It was clear that there was improvement, but I still didn't know whether it was as much improvement as I should have expected.
Then all the photos made it up to iCloud Photo Library, and back down to my Mac. And now I don't wonder at all. The new photos were CLEARLY, at a glance, better than the older ones. More detail pulled out of darker areas, better color. The sharpness is still similar when zoomed down to look at elements really close up...but the better color detail just brings it all into much better focus.
I am so relieved.
EDIT: I added three images: one (unmarked) from the old SE, one from the 2020 SE, and one from my old 3GS (hehe). I had another image that was a more striking difference, but looking at them I fear that perhaps I focused (or, more to the point, light-metered) on different locations. I don't THINK I did, but i FEAR I did, so I think it would not have been a fair comparison. Anyway, the example I attached should give you a fair idea. No editing done, except to add the text.