IMHO the new theme was not very well thought out. Among many poor decisions was increasing the radius of the rounded corners. Besides being visually unappealing (IMHO), you end up with this:

That's the corner cutting off the scroll bar of the System Settings window. Maybe the designers decided it was okay, or maybe they didn't consider it. Either way, it comes across as amateurish.
I also find window edge elements - title bar, status bar, scroll bars, etc. - to be a bit too large, resulting in a "chunky" appearance that looks imbalanced, somewhat dwarfing the folder elements, not to mention using that much more screen real estate. And moving the folder name to the left...why? Especially when the information of the status bar is still centered. It just looks off, having all of the title bar elements on one side.
I've come across some non-theme bugs as well, although maybe they have to do with apps needing to be updated after updating the OS to Tahoe. For example, Firefox randomly forgot all of the autocompletes I relied on for frequently visited websites, but not immediately after the OS update, it was several restarts later. (I did not change anything with Firefox in that time.) Sometimes Linear Mouse would not launch (I have it as a startup item, but even if I try to launch it manually, it can take multiple tries). And if I have multiple browser windows open, sometimes one window would become inaccessible by mouse click or by Cmd-` until I switch to a different app and back again. I regret updating from Sequoia, which I already didn't like due to the iPhonification of the UI since Ventura.