The function of a UI should be to get to the most used functions as quickly as possible. As such, it fails in several ways. Trophies take too many button presses to get to and turning the console off takes WAY too many and it's bizarre that it got through in such a state.
Video/screen captures take too long to get to unless you've recently opened it up. They should be in the Game Base.
The Switcher would be useful if Quick Resume existed on PS5, but without it it feels useless.
Trophies list should be vertical rather than horizontal. They're trying to have design consistency with Activity Cards, but they don't need to.
I think those are my main problems with the UI. On the positive side, it's very quick, extremely pretty/sleek/smooth, keyboard is just fantastic, I love the main home screen design, LOVE having the store, the collection. the Playstation Plus stuff, etc all PERFECTLY integrated into the UI with no screen jumps.
It's honestly a great UI that needs some serious tweaks.