Solasta's UI is clean, clear, intuitive, easy to read and follow, and remarkably bug free in its execution. BG3's UI is exactly none of those things at the present time.
The only complaint I've ever seen anyone make about Solasta's UI is that they feel its aesthetic doesn't fit with a fantasy D&D game, or that they simply don't find it aesthetically appealing. I've never seen any complaints related to its actual function.