Mostly, the inconsistent camera. Sometimes photos would come up great, but sometimes they would be of a really disappointing quality for a flagship phone. And this even in perfect light conditions.
Another issue was occasional lag / UI hiccups, even if situation improved a lot with updates and lag was mostly gone. Still, I'm positive that S21U which I had before S22U was more snappy.
Batt life was ok for me, somewhere around 6,5-7,5 hours SOT.
Also, I have the impression that device would overheat a lot in the summer. With outside temp around 28-30°C I already noticed some throttling.
I had exynos version.
Other than that, it is a great device and I actually like OneUI experience a lot. Probably I would keep it till next year because, other than Vivo, I don't see anything appealing on the market right now. Ok, perhaps Oppo Find X5 pro, but this device has only 2x zoom camera and without OIS.