Alright, so I did a deep side-by-side comparison today of my S21 Ultra and S22 Ultra before trading the former in. My thoughts so far, YMMV:

Things to note, while comparing I had them both on the same settings for display, brightness, volume, and battery (both were fully charged). The S22U was on the Jan security patch while S21U was on the Feb patch. Both are T-Mobile versions. Both are the snapdragon versions (888 and 8G1).

Display:

S22U is notifiable brighter but not by much. Color temperature was definitely different for both the phones even after setting them up as similarly as possible. The S21U was slightly warmer colors than S22U. But this can be due to panel variance and is not anything major or of concern.

I did an HDR video playback test on both phones at the same time. Initially, the S22U screen flickered in brightness A LOT while playing back HDR video. After restarting the phone it seemed to have been fixed but overall the dynamic range of S21U definitely looked better to my eyes. I watched around 3 HDR videos at the same time.

Sound:

Clear winner: S21U by a significant margin. No matter what setting I changed or tweaked, I could not get the S22U speakers to sound close to S21U. The S22U speakers sounded tinier in comparison and had much less tight bass.

Like MKBD mentioned in his video, the vibration motor alignment was changed by Samsung which drastically reduces the perception of haptics at the same setting. Again not too major but it bothers me since I keep my phone on vibrate mode most of the time.

Aesthetics and Looks:

The back of the S22U looks much cleaner without any camera bump. I am impressed. But the added width definitely makes the phone feel significantly larger and more difficult to hold with one hand. This is a major issue for me.

Camera:

Rear camera: S22U is the clear winner, hands down. Better focus, colors, and low light compensation.

Front camera: For some reason, the colors and sharpness of the front camera are off on the S22U. There also seem to be some focus issues when compared to the S21U. Might be an issue with my unit, I am not sure.

Performance:

There is some lag while scrolling on the S22U similar to the issue S21U had when OneUI 4.0 was released. It's not as bad but is noticeable sometimes. Again nothing major and would probably be fixed in a software update. Thermals seem similar, although my S21U heated up and throttled often while gaming, so I don't think the S22U can be worse than that.

Overall, I have decided to return the S22U. Cost-wise, bundling with the Tab S8 ultra made the "upgrade" from S21U almost free, but it doesn't feel like an upgrade. The spen is great, but I don't use it enough for me to overlook the other things wrong with the S22U. Most of the things I have mentioned are fixable in future software updates, but the form factor is still an issue.

I'm currently on an S20, which is getting old and has a damaged screen, so I'm thinking about getting a newer phone. S23 and S22 ultra are out of my preferred budget, so the two options I seem to have are the S22 (or S22+) and S21 Ultra. Any thoughts on which might be best? They are around the same price, with the 21 ultra being slightly cheaper where I live.