It's about 60% as usable. Weird and distracting jiggling makes it hard to target where the button will be.

Also the placement of buttons and functionality is completely scattered around the UIs, which severely reduces usability. What do all the mystery meat buttons do now? One has to relearn all the UX. There's a ton of improvement needed, it's about first-draft level quality.

Dark mode UI elements are almost invisible too, frequently.

It has a "my first redesign project" feel everywhere. On macOS I upgraded right away and it was a huge downgrade on performance. On iPhone I waited until 26.2, and merely had to suffer far lower usability.